Present writer adopts son (4)
I believe the answer is:
pose
'present' is the definition.
(synonyms)
'writer adopts son' is the wordplay.
'writer' becomes 'poe' (Edgar Allan Poe).
'adopts' is an insertion indicator.
'son' becomes 's'.
'poe' placed around 's' is 'POSE'.
(Other definitions for pose that I've seen before include "Sit for picture" , "Sit (for an artist)" , "Sit for a painter" , "Pretend; model" , "Present (problem), sit" .)