Part of a doorframe (4)
I believe the answer is:
jamb
'part of a doorframe' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for jamb that I've seen before include "Side post of a doorway" , "Doorpost" , "bit on the side?" , "Door-frame side" , "Vertical part to a doorframe" .)