Shoot, not initially in anger (3)
I believe the answer is:
ire
'anger' is the definition.
(ire is intense rage)
'shoot not initially' is the wordplay.
'shoot' becomes 'fire' (as in firing a gun).
'not initially' means to remove the first letter.
'fire' with its initial letter removed is 'IRE'.
'in' is the link.
(Other definitions for ire that I've seen before include "Anger among admirers" , "resentment" , "Fury" , "Anger, annoyance" , "Losing head" .)