King dismissed crushing defeat (4)
I believe the answer is:
rout
'crushing defeat' is the definition.
(I've seen this in another clue)
'king dismissed' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'dismissed' becomes 'out' (dismissed in cricket).
'r'+'out'='ROUT'
(Other definitions for rout that I've seen before include "Whitewash" , "snore" , "Defeat utterly" , "Vanquish; thrash" , "Defeat comprehensively" .)