Noise of complaint increased in the auditorium (5)
I believe the answer is:
groan
'noise of complaint' is the definition.
'increased in the auditorium' is the wordplay.
'increased' becomes 'grown' (I've seen this before).
'in the auditorium' shows a homophone (sound like) (ie as heard on a stage).
'grown' is a homophone of 'GROAN'.
(Other definitions for groan that I've seen before include "Sound pained; Gormenghast earldom" , "Sound of pain or despair" , "Make pained sound" , "painful sigh" , "Organ (anag) - lament" .)