Fifteensquared

A rather work-a-day puzzle, I fear. 1A provided an easy entry, and then gravity pretty much took care of the remainder.  11A raised a smile, but I was underwhelmed by 18D on a couple of scores.

Across
1 FINGER PAINTING- cryptic def’n.  The “digital” pun has become a fairly well-worn path in recent times.
10 OMANI – (in a mo)<.
11 YARD OF ALE – (a Rd of) in Yale.
12 BOOKFUL - cryptic def’n.
13 ALFALFA - Alf (x2) + a{gency}.  Lucerne here in the botanical, rather than geographic, sense.
14 TRESS – {s}tress.
16 INDENTURE – ENT (ear/nose/throat) in (ruined)*.
19 JET-SETTER -  a fun clue, but certainly stirred vague memories of having encountered similar previously.
20 ELDER- double def’n.
22 COCHLEA – this didn’t strike me as particularly cryptic, unless you happen to be unfamiliar with the slang term “shell-like”.
25 INTERIM – inter + I’m.
27 EXPORTING – hidden.
28 IDEAL - “I deal”.
29 SAINT ELMO’S FIRE – (is lit for seamen)*. Well, at least there’s an irresistible opportunity for me to resurrect gratuitous 80′s pop culture link of the day.

Down
2 IN A MOMENT – (man on time)*.
3 GRIEF – initial letters.
4 ROYAL MINT – (normality)*.
5 AORTA - (0 + R) in a + TA.
6 NO OFFENCE- figurative/literal double def’n.
7 IN ALL – Na (sodium) in ill.
8 GRENADE – E[cstasy] in danger*.
9/19 COMBAT JACKETS- punning def’n.
15 SMELL A RAT – a play on mixing olfactory/zoological metaphors.
17 DERRING-DO – Der + ring + do.
18 UNDERWEAR – as seen twice in “bravest”.  Another old-as-the-hills device, but with the bonus quibble that the cyptic reading requires “displays” rather than “display”.
21 RAMBLE- double def’n.
23 CAPRI – capri{corn}.
24 ARIEL- double def’n. 
26 THIEF - re: the phrase “All property is theft”.