Urge to act (4)
I believe the answer is:
prod
'urge to act' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for prod that I've seen before include "Poke, jab, nudge" , "Give a reminder" , "Provide stimulation" , "Poke with a stick" , "Goad, stimulate into action" .)