Ask to sit (4)
I believe the answer is:
pose
I believe this clue is a double definition.
'ask' is the first definition.
(synonyms)
'to sit' is the second definition.
(as in sitting for a painter)
(Other definitions for pose that I've seen before include "Model; attitude" , "Present (a question); sit" , "Sit for picture" , "Sit (for an artist)" , "Stance - attitude" .)