Increase level for audience (5)
I believe the answer is:
raise
'increase' is the definition.
(I know that raise is a type of increase)
'level for audience' is the wordplay.
'level' becomes 'raze' (synonyms).
'for audience' indicates a 'sounds like' (homophone) clue (how it might sound to an audience).
'raze' sounds like 'RAISE'.
(Other definitions for raise that I've seen before include "Lift - increase" , "jack up" , "Hoist" , "What a poker player might do" , "Uplift" .)