Looks for audience: they fit in well (6)
I believe the answer is:
stairs
'they fit in well' is the definition.
(stairs go in a stairwell)
'looks for audience' is the wordplay.
'looks' becomes 'stares' (stare is a kind of look).
'for audience' indicates a 'sounds like' (homophone) clue.
'stares' is a homophone of 'STAIRS'.
(Other definitions for stairs that I've seen before include "Flights of steps" , "Interior means of ascent" , "Ascending flight of steps" , "Series of steps" , "Access consisting of steps" .)