Athlete's jitters (4)
I believe the answer is:
yips
'athlete's jitters' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for yips that I've seen before include "Nervous twitching in a golfer" , "Nervous tension that lets a golfer down?" , "nervous reaction" , "Golfer's affliction" , "Yelps" .)