Prod about masculine post (4)
I believe the answer is:
jamb
'post' is the definition.
(I've seen this before)
'prod about masculine' is the wordplay.
'prod' becomes 'jab' (synonyms).
'about' indicates putting letters inside.
'masculine' becomes 'm'.
'jab' going around 'm' is 'JAMB'.
(Other definitions for jamb that I've seen before include "Upright of door" , "Doorpost" , "Door-frame side" , "bit on the side?" , "Side of door frame" .)