Best employees have to stop (4)
I believe the answer is:
stem
'stop' is the definition.
(stem can mean to stop or interrupt)
'best employees have' is the wordplay.
'have' says the answer is hidden in the clue.
'STEM' is hidden in the letters of 'best employees'.
'to' acts as a link.
(Other definitions for stem that I've seen before include "Stop or slow the flow of" , "Central upright part of flower or drinking glass" , "Ski turn and plant support" , "Slender upright part, of flower or wineglass" , "Stop the flow of, check" .)