Last employees have to stop (4)
I believe the answer is:
stem
'stop' is the definition.
(stem can mean to stop or interrupt)
'last employees have' is the wordplay.
'have' indicates a hidden word.
'STEM' is hidden in the letters of 'last employees'.
'to' acts as a link.
(Other definitions for stem that I've seen before include "'Stalk, shank (4)'" , "Stalk - check" , "Basic skiing turn" , "supporter of flag, for example" , "Restrain - staunch - supporter" .)