Maximum resentment, by the sound of it (4)
I believe the answer is:
peak
'maximum' is the definition.
(similar in meaning)
'resentment by the sound of it' is the wordplay.
'resentment' becomes 'pique' (I've seen this in another clue).
'by the sound of it' shows a homophone (sound like).
'pique' is a homophone of 'PEAK'.
(Other definitions for peak that I've seen before include "Pinnacle" , "Sharp pointed summit" , "Part of cap; mountain" , "High point" , "Pointed mountain" .)