Men caught a whale (4)
I believe the answer is:
orca
'whale' is the definition.
(I know that orca is a type of whale)
'men caught a' is the wordplay.
'men' becomes 'OR' (Other Ranks: non-commissioned soldiers).
'caught' becomes 'c' (cricket abbreviation).
'or'+'c'+'a'='ORCA'
(Other definitions for orca that I've seen before include "27 [WHALE]" , "Predatory black and white toothed whale" , "grampus" , "Large predator" , "Danger for swimmers" .)