Abuse Frenchman caught slashing fixed discount (10)
I believe the answer is:
misconduct
'abuse' is the definition.
(thesaurus)
'frenchman caught slashing fixed discount' is the wordplay.
I cannot really see how this works, but
'frenchman' could be 'm' (abbreviation for Monsieur - like 'Mr') and 'm' is found in the answer.
'caught' could be 'ct' and 'ct' is present in the answer.
This explanation may well be incorrect...
(Other definitions for misconduct that I've seen before include "Bad behaviour" , "Improper behaviour" , "Immorality" , "wrongdoing" .)