Pals out on strike (4)
I believe the answer is:
slap
'strike' is the definition.
(I know this)
'pals out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'pals' anagrammed gives 'SLAP'.
'on' acts as a link.
(Other definitions for slap that I've seen before include "Hit with an open hand" , "Make-up (slang)" , "Blow, maybe in the face" , "Strike action" , "A blow among pals" .)