Stuck On Several- Help Please

[venator]

12ac Pensioner: a kind, withdrawn, accommodating woman (5) K?R?? KAREN, but why?
16d Did arias, maybe, getting rid of alternative being composed
in conservatoire? (9) S?n???o??
24ac Eat: start on tongue (6,3)??????O??
15d Wine and last of beer that is had with spirit drink (8) R?E???N?

here are a few more, but shame prevents me from asking...

[Captain2]

15 Riesling

[Flonska]

12 PensioNER A Kind (hidden in the clue)

[Lie-in King]

12a Karen - back, in 'pensio NER A K ind...'
16d Sangfroid - 'sang' (did arias) + anag 'rid of'
24a Polish off - 'Polish' (tongue) + 'off' (start)
15d Riesling - '(bee)r' (last) + 'ie' (that is) + 'sling' (spirit[-based] drink)

[dannyk13]

12a.Reversed in clue- PensioNER A Kind

[Flonska]

16d Sang froid