Choosy, asks selection to be held up for approval (3-2)
I believe the answer is:
say-so
'approval' is the definition.
(I've seen this in another clue)
'choosy asks selection to be held up' is the wordplay.
'to be held' indicates the answer is hidden within the clue.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'osyas' is hidden within 'choosy asks selection'.
'osyas' in reverse letter order is 'SAY-SO'.
'for' is the link.
(Other definitions for say-so that I've seen before include "Go-ahead" , "Authority - rumour" , "Final authority" , "Final approval" , "Authority to make a decision" .)