Salad green for some wiseacre's son (5)
I believe the answer is:
cress
'salad green' is the definition.
(cress is a kind of salad green)
'some wiseacre's son' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'CRESS' is hidden in the letters of 'wiseacres son'.
'for' acts as a link.
(Other definitions for cress that I've seen before include "bit of salad" , "Salad vegetable" , "Salad sprouts" , "Plant with pungent leaves used in salads" , "Green cold salad ingredient" .)