Financial Times 13,504 / Flimsy

Plenty of Flimsy whimsy in evidence today, although I thought that a couple of clues (12A, 19A) were, in part, too lazily self-referential.  On the plus side, I learned a geographic factoid courtesy of fact-checking the clue to 10A.

Across
1 WINDJAMMER – wind + jam me + r{uddy}.
4 DEFT – ed< + FT.
9 THAI – hidden.
10 IRRELEVANT – (River Lena)* + t[emperature].  Apparently the Lena is the 11th longest river in the world.  Perhaps it should consider hiring a better PR agent?
11 WRITER – homophone of “right”+ r[uns].
12 EYEGLASS – eye + G + lass.
13 STRIKING – double def’n.
15 PEER – pee + R. ‘Go’ in the lavatorial sense.
17 ORAL – {m}oral.
19 RESCRIPT – re: + script.
22 GANGRENE – gang + René.
23 AFLOAT – a[cccepted] + float.
25 FIELD TRIPS – field + trips.  Twenty years on, I’m still haunted (“tor”mented?) by scholastic memories of a couple of days of investigating the storm-swept terrain of Dartmoor – all in the name of GCSE Geography.
26 NEED – need{le}.
27 DENY – Ned< + y[ard].
28 ENGINE ROOM – E[nergy] +g[ood] in (in Rome)*.

Down
2 INHERIT – (in the IR)*.  A little indirectness in the anagram fodder, but I’m willing to indulge it for the concise/coherent surface.
3 DRIFT– d{runk} + rift.
4 ACID RAIN – cryptic def’n.  Although it read very transparently to me.
5 MARKET GARDENING – (danger)* in marketing. In the US, a market garden is known (far more prosaically) as a truck farm.
6 ROLLER – double def’n.
7 DEVELOPER – (deep love)* + R[esistance].  This one raised the biggest smile, so is the de facto clue of the day.
8 FINESSE – (Essen + if)*.
14 ILLEGALLY – ill + galley, with the e promoted.
16 ASSASSIN – ass x2 + ni{b}<.
18 REALISE – (See rail)*.
20 PLACEBO – place + B.O. (there’s been a lot of this in the air recently, it seems).
21 SEETHE – see + het*.
24 LINER – (Nile)* + r.