Our man's wild and king goes crazy (4,4)
I believe the answer is:
runs amok
'goes crazy' is the definition.
(I've seen this before)
'our man's wild and king' is the wordplay.
'wild' indicates anagramming the letters.
'and' is a charade indicator (letters next to each other).
'king' becomes 'K' (abbreviation for king in chess).
'our'+'mans'='ourmans'
'ourmans' is an anagram of 'runsamo'.
'runsamo'+'k'='RUNS AMOK'
(Other definitions for runs amok that I've seen before include "Goes crazy" , "Loses control" , "Attacks people violently and without discrimination" , "riots" .)