Worker completed transfer (4,4)
I believe the answer is:
hand over
'transfer' is the definition.
(thesaurus)
'worker completed' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'completed' becomes 'over' ('over' can be a synonym of 'completed').
'hand'+'over'='HAND OVER'
(Other definitions for hand over that I've seen before include "Deliver into control of another - in manual way?" , "Present or give to another person - manually?" , "Transfer" , "Pass across; surrender" , "Yield possession of in overhand way" .)