Cease working (6)
'cease working' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for retire that I've seen before include "Pull back" , "Get your head down" , "Give up working and go to bed" , "Leave work; go back" , "Give up work for good" .)
(Other definitions for strike that I've seen before include "Deliver a blow" , "Song of regret" , "Attack - industrial action" , "Hit with picket?" , "Downing of tools" .)