Sneering scars a distressed Frenchman (7)
I believe the answer is:
sarcasm
'sneering' is the definition.
(thesaurus)
'scars a distressed frenchman' is the wordplay.
'distressed' is an anagram indicator.
'frenchman' becomes 'm' (abbreviation for Monsieur - like 'Mr').
'scars'+'a'='scarsa'
'scarsa' is an anagram of 'sarcas'.
'sarcas'+'m'='SARCASM'
(Other definitions for sarcasm that I've seen before include "Ironic wit" , "Mordancy" , "Ironically scornful language" , "Scornful attitude" , "Satirical and scornful remarks" .)