Bulge in pants covered by prig (8)
I believe the answer is:
protrude
'bulge' is the definition.
(I know that bulge is a more specific form of the action protrude)
'pants covered by prig' is the wordplay.
'pants' becomes 'rot' (both can mean rubbish or nonsense).
'covered by' means one lot of letters goes inside another.
'prig' becomes 'prude' (I've seen this before).
'rot' put inside 'prude' is 'PROTRUDE'.
'in' is the link.
(Other definitions for protrude that I've seen before include "Stick out, project from a surface" , "Stand out" , "Thrust forward" , "Jut out" , "Push forward" .)