Comrades turning up for strike (4)
I believe the answer is:
slap
'strike' is the definition.
(slapping is a kind of striking)
'comrades turning up' is the wordplay.
'comrades' becomes 'pals'.
'turning up' says the letters should be written backwards.
'pals' backwards is 'SLAP'.
'for' acts as a link.
(Other definitions for slap that I've seen before include "Blow (in face, on back, wrist)" , "Make-up (slang)" , "Hit with the palm" , "Sharp smack" , "Blow with open hand" .)