Moaned audibly after hip locked up (6)
I believe the answer is:
inside
'locked up' is the definition.
(I've seen this before)
'moaned audibly after hip' is the wordplay.
'moaned' becomes 'sighed' (I've seen this before).
'audibly' indicates a 'sounds like' (homophone) clue.
'after' means one lot of letters go next to another.
'hip' becomes 'in' (both can mean fashionable).
'sighed' is a homophone of 'side'.
'side' put after 'in' is 'INSIDE'.
(Other definitions for inside that I've seen before include "(Of information) from a confidential source" , "Within - interior" , "confined" , "Enid is (anag) - within" , "Privileged" .)