Voice disapproval of Mike’s resonant delivery? (4)
I believe the answer is:
boom
'resonant delivery?' is the definition.
(as in a booming voice)
'voice disapproval of mike's' is the wordplay.
'voice disapproval of' becomes 'boo' (to boo something is to voice disapproval of it).
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'boo'+'m'='BOOM'
(Other definitions for boom that I've seen before include "Resound - spar - economic growth" , "Deep hollow sound" , "time of 22 [PROSPERITY]" , "Prosperity - hollow roaring noise" , "Cry of the bittern" .)