Cashier blowing top in fury (3)
I believe the answer is:
ire
'fury' is the definition.
(I've seen this before)
'cashier blowing top' is the wordplay.
'cashier' becomes 'fire' (cashier can mean to fire or dismiss a soldier).
'blowing top' means to remove the first letter.
'fire' with its first letter taken off is 'IRE'.
'in' acts as a link.
(Other definitions for ire that I've seen before include "Choler" , "Hot temper" , "Annoyance, vexation" , "Strong feeling" , "Losing head" .)