His temper has to stop (4)
I believe the answer is:
stem
'stop' is the definition.
(I know that stem is a more specific form of the action check)
'his temper has' is the wordplay.
'has' indicates the answer is hidden within the clue.
'STEM' is hidden within 'his temper'.
'to' acts as a link.
(Other definitions for stem that I've seen before include "Restrict - part of a plant" , "Central upright part of flower or drinking glass" , "Hold back - stock - check" , "Slender upright part, of flower or wineglass" , "branch of family" .)