Some off-beat definitions make this an interesting solve, and a possible mistake? Thank you Alberich.

Across | ||
1 | PASSIM | Retiring young woman follows secretary everywhere (6) |
MISS (young woman) reversed (retiring) follows PA (secretary) | ||
5 | ASTERISK | Star is beset by heartless stalker, possibly (8) |
IS inside (beset by) anagram (possibly) of STALKER missing middle letter (heartless) | ||
9 | HAIRGRIP | Look gross, wearing trendy item for shock? (8) |
AIR (look) GR (gross) inside (wearing) HIP (trendy) – an item for a shock of hair | ||
10 | IODINE | I will have ten to lunch? (6) |
IO (10, ten) with (to) DINE (lunch?) – I is chemical symbol for Iodine | ||
11 | Blue suit keeps one extremely happy (6) | |
I think this is probably FILTHY (blue) – FIT (suit) contains (keeps) L (one ?) then HappY (extremes of) | ||
12 | ASTEROID | Running or a diet’s producing a heavenly body (8) |
anagram (running) of OR A DIET’S | ||
14 | HUDDERSFIELD | Town hall’s beginning to deal with surrounding parts of Ayrshire? (12) |
Hall (first letter, beginning) FIELD (to deal with, eg field a question) contain UDDERS (parts of Ayrshire, a breed of cow) | ||
18 | PARSIMONIOUS | Playing possum on air to trap one? That’s mean (12) |
anagram (playing) of POSSUM ON AIR contains (to trap) I (one) | ||
22 | PHASE OUT | What makes shape gradually terminate? (5,3) |
a reverse clue: anagram (OUT) of PHASE makes “shape” | ||
25 | WALLOP | Washington backed vote to strike (6) |
WA (Washington) then POLL (vote) reversed (backed) | ||
26 | FORGET | Stop thinking about fashion trends, for a start (6) |
FORGE (fashion) then first letter (for a start) of Trends | ||
27 | PATHETIC | Lamentable way to quote revolutionary (8) |
PATH (way) them CITE (to quote) reversed (revolutionary) | ||
28 | IMPAIRED | Challenged self-description of one who’s married? (8) |
I’M PAIRED is a self-description of one who’s married | ||
29 | HITHER | Success gets the woman to this place (6) |
HIT (success) with HER (the woman) | ||
Down | ||
2 | ADAGIO | Slowly a soldier gets into trouble (6) |
A GI (soldier) inside ADO (trouble) | ||
3 | SCRATCHES | Scores runs, restrained by first of several dismissals (9) |
R (runs) inside (restrained by) Several (first letter of) CATCHES (dismissals, in cricket) | ||
4 | MARTYRDOM | Suffering from advanced dry rot? That’s sorted in minutes (9) |
A (advanced) and anagram (that;s sorted) of DRY ROT inside M M (minute, twice) | ||
5 | APPEASE | Calm primate eats seeds (7) |
APE (primate) contains (eats) PEAS (seeds) | ||
6 | TAINT | It is not pollution (5) |
double definition – ‘TAINT (it is not) | ||
7 | RIDER | One up on gossip shortly returned (5) |
RE (on) DIRt (gossip, shortly) all reversed (returned) – up on a horse | ||
8 | SENSIBLE | Left bins out in sight? That’s wise (8) |
anagram (out) of L (left) BINS inside SEE (sight) | ||
13 | ELF | Periodically tell off mischievous creature (3) |
every other letter (periodically) of tElL oFf | ||
15 | STOPWATCH | Sample sandwiches Kitty served up? This’ll give you time (9) |
SWATCH (sample) contains (sandwiches) POT (kitty) reversed (served up) | ||
16 | INSOLVENT | Having brass around versus having no brass? (9) |
INSOLENT (having brass) contains (around) V (versus) | ||
17 | BATHROOM | Place for washing cleaner clothes at hospital (8) |
BROOM (a cleaner) contains (clothes) AT H (hospital) | ||
19 | ICE | Reserve majestic Edwardian houses (3) |
found inside (housed by) majestIC Edwardian | ||
20 | NOTEPAD | To pen a novel, initially defeat writer’s block? (7) |
anagram (novel) of TO PEN A then Defeat (first letter of, initially) – a block of paper | ||
21 | MOTIVE | Persuade to keep it up, offering inducement (6) |
MOVE (persuade) contains (to keep) IT reversed (up) | ||
23 | SIGMA | Mark has no time to produce letter (5) |
StIGMA (mark) missing T (time) | ||
24 | OTTER | Rock decapitated aquatic creature (5) |
tOTTER (rock) missing first letter (decapitated) |
definitions are underlined
I write these posts to help people get started with cryptic crosswords. If there is something here you do not understand ask a question; there are probably others wondering the same thing.
Loved this. Lots of beautifully constructed clues, such as those for: IODINE, BATHROOM, NOTEPAD & INSOLVENT. But what happened with 11a? I came to the same conclusion as you PeeDee. Many setters make use of a checker but it is hard to believe any checker would not have flagged this up – or maybe there’s another explanation?
Thanks to Alberich and PeeDee.
Nonetheless this blue suit was kept extremely happy. Being filthy is still an ambition. Many thanks, Alberich.
Thanks Alberich and PeeDee
A really entertaining crossword despite the little glitch with the word play of FILTHY.
That whole top left corner took as long to complete as the rest of the puzzle, having initially written in HAIRCLIP (with misgivings about the CL) at 9a and an even more whimsical MILDEWDOM at 4d. Eventually settled on 11a finishing with -HY, which allowed me to correct MARTYRDOM and HAIRGRIP and finally put in FILTHY with the conclusion that there must be an incorrect clue.
Couldn’t completely parse HUDDERSFIELD (not seeing that definition of FIELD).
Continue to appreciate (and be tricked for a while) with clues using the chemical symbol as the definition – like I=iodine, AS=arsenic, etc.
Very enjoyable with mostly excellent clues. Thanks Alberich!