Nasty noise increased for listeners … (5)
I believe the answer is:
groan
'nasty noise' is the definition.
'increased for listeners' is the wordplay.
'increased' becomes 'grown' (I've seen this before).
'for listeners' indicates a 'sounds like' (homophone) clue (I've seen 'for Listener' mean this).
'grown' sounds like 'GROAN'.
(Other definitions for groan that I've seen before include "Utterance expressing pain or disapproval" , "Moan, grumble" , "Express disappointment, pain" , "Complaint" , "See 18 Down" .)