Lively exchange of views annoyed cashier (9)
I believe the answer is:
crossfire
'lively exchange of views' is the definition.
(I've seen this before)
'annoyed cashier' is the wordplay.
'annoyed' becomes 'cross' (cross can mean angry).
'cashier' becomes 'fire' (cashier can mean to fire or dismiss a soldier).
'cross'+'fire'='CROSSFIRE'
(Other definitions for crossfire that I've seen before include "bullets coming from all sides" , "argument" , "lively exchange of opinions" , "Hail of bullets" , "fierce exchange" .)