I enjoyed this very much.  In the Goldilocks zone for me: neither too easy nor hard; inventive but not flashy; general knowledge but not a quiz; generally just right for a morning coffee solve.  Thanks Sleuth.

| Across | ||
| 1 | MOONSCAPE | Instant ocean’s made out around front of planet – familiar sight for astronauts? (9) | 
| MO (moment, instant) with anagram (made out) of OCEAN’S containing Planet (first letter of) | ||
| 6 | CATCH | Understand concealed difficulty (5) | 
| double definition | ||
| 9 | CONDUCT | What lead can do is to lead players? (7) | 
| double definition | ||
| 10 | BIRYANI | Indian dish served back in a yard by guy (7) | 
| IN A Y (yard) by RIB (guy, to make fun of) allreversed (served back) | ||
| 11 | ODOUR | Savour European river when cycling (5) | 
| DOURO (European river) with the letters rotated one place (last letter moves to the front) | ||
| 12 | ESPERANTO | Inventive poet’s near universal language (9) | 
| anagram (inventive) of POET’S NEAR | ||
| 14 | AWL | Boring instrument everyone mentioned (3) | 
| sounds like (mentioned) all (everyone) | ||
| 15 | CHOLESTEROL | Old lecturer probing part of body and learning about source of blockage? (11) | 
| O (old) L (lecturer) inside (probing) CHEST (part of body) and LORE (learning) reversed (about) | ||
| 17 | COME TO BLOWS | Police beside old British base in island start fighting (4,2,5) | 
| MET (Metropolitain Police) with O (old) B (British) LOW (base) in COS (an island) | ||
| 19 | KOI | I approve in retirement exotic fish (3) | 
| I OK (approve) reversed (in retirement) | ||
| 20 | SOAP OPERA | TV staple provided by a poet and artist (4,5) | 
| SO (provided) by A POPE (Alexander Pope, poet) and RA (Royal Academician, artist) | ||
| 22 | ADMIT | Acknowledge daughter in unending friendship (5) | 
| D (daughter) in AMITy (friendship, unending) | ||
| 24 | ROUTINE | Element in profligate that’s unvarying (7) | 
| TIN (element) in ROUE (profligate) | ||
| 26 | INEXACT | Unclear tax since modified with no end of fuss (7) | 
| anagram (modified) of TAX sINCE missing S (end letter of fuss) | ||
| 27 | LIE-IN | Extended period for kippers? (3-2) | 
| cryptic definition | ||
| 28 | FREE TRADE | Liberal economic tenet that could be rated? (4,5) | 
| an anagram (FREE) of TRADE could be “rated”. | ||
| Down | ||
| 1 | MACHO | Very aggressive companion restrained by chairman (5) | 
| CH (Companion of Honour) inside MAO (chairman) | ||
| 2 | OWN GOAL | No-go law to be scrapped – self- inflicted mistake (3,4) | 
| anagram (to be scrapped) od NO-GO LAW | ||
| 3 | SQUARE-CUT | Old-fashioned copper on time with a strong jaw? (6-3) | 
| SQUARE (old fashioned) CU (copper) on T (time) | ||
| 4 | AT THE DOUBLE | Erratic tube loathed very quickly (2,3,6) | 
| anagram (erratic) of TUBE LOATHED | ||
| 5 | EBB | Some web businesses in decline (3) | 
| found inside wEB Business | ||
| 6 | CARER | Rush with energy once depleted to get aid for the vulnerable (5) | 
| CAREeR (rush) missing E (energy, only once) | ||
| 7 | TRAINER | Pitman, say, with skill put up with pitman initially deficient (7) | 
| ART (skill) reversed (put up) with mINER (pitman) missing first letter – the Pitman training company was established in 1886 by Sir Isaac Pitman | ||
| 8 | HOI POLLOI | Mass in Athens? (3,6) | 
| cryptic definition? | ||
| 13 | PREROGATIVE | Right in power with right backing Argentinian and US politician (11) | 
| P (power) and R (right) reversed (backing) EVITA (Argentinian) and GORE (US Politician) – I am interested to learn that I have been mis-hearing this word as PEROGATIVE for years. | ||
| 14 | ANCESTRAL | A new claret’s ordered – typical of some stately homes? (9) | 
| anagram (ordered) of A N (new) and CLARET’S | ||
| 16 | TESTAMENT | Match last word and last letter in bequest in will (9) | 
| TEST (cricket match) AMEN (last word) bequesT (last letter of) | ||
| 18 | MEASURE | Complaint with a certain length? (7) | 
| ME (complain, illness) with A SURE (certain) | ||
| 19 | KAMPALA | Knight, a scholar entertaining friend in capital (7) | 
| K (knight) with A MA (scholar) containing (entertaining) PAL (friend) | ||
| 21 | ORION | Hunter among Maori onlookers (5) | 
| found inside maORI ONlookers | ||
| 23 | TITLE | Noble feature in book (5) | 
| double definition | ||
| 25 | ELF | Unlimited pottery showing supernatural being (3) | 
| dELFt (pottery) with no end letters (unlimited) | ||
*anagram 
definitions are underlined
Thanks, PeeDee.
I agree entirely with your preamble – I enjoyed it very much, too, particularly the clue for CHOLESTEROL, so many thanks to Sleuth.
[I don’t think you’ve been mishearing, PeeDee – that’s the way most people seem to pronounce it. 😉 ]
Thanks PeeDee and Sleuth.
I needed your help to understand ODOUR – much appreciated.
I too concluded that HOI POLLOI was a cryptic but would normally expect “the masses” rather than “mass”.
I’m not really sure about “so” = “provided” in 20 across – can’t think of an example where they’d be interchangeable. Any ideas?
Nevertheless, appreciate the challenge.
The Collins on kindle gives so-provided as archaic. I don’t have any other dictionary to hand.
Thanks 🙂 Could not parse cholesterol, Odour and Biryani.. Guy = rib clevva 🙂
Thanks Sleuth and PeeDee.
Re 7D, though I’d heard of Isaac Pitman in relation to shorthand, I didn’t realise that he’d started a training company and had assumed the definition was referring to Jenny Pitman (the racehorse trainer) instead.
Jenny Pitman sounds more likely to me. I was not very happy about Isaac Pitman, who as you say is better known for shorthand.
Thanks Sleuth and PeeDee
A spare moment to get back to one of the backlog puzzles and quite a good one at that. Was able to get most of it out on a 25 minute train ride and a couple of shorter sessions to mop it up.
Had the wrong river at 11 and tried not too successfully to do something with ODER – so thanks for setting that straight. A couple of complicated charades to keep one honest in the other clues – in particular 10a, 15a (which I agree was very good), 20a, 13d and 19d.
I went with the Pitman Training Company as the ‘trainer’ after looking it up – but now looking up the horse trainer can understand that it could have been her that was meant as well.
Finished down in the SE corner with FREE TRADE and TITLE.