Still a fixture of theatre stalls (2,4)
I believe the answer is:
at rest
'still a fixture' is the definition.
'at rest' can be an answer for 'still' (I've seen this in another clue). I am not sure about the 'a fixture' bit.
'of theatre stalls' is the wordplay.
'of' indicates the answer is hidden within the clue.
'AT REST' is hidden within 'theatre stalls'.
Can you help me to learn more?
(Other definitions for at rest that I've seen before include "Motionless" , "Sleeping peacefully - maybe dead" , "Not moving, free from anxiety" , "late" , "Still" .)