Plea from French criminal (7)
I believe the answer is:
defence
'plea' is the definition.
(thesaurus)
'from french criminal' is the wordplay.
'from french' becomes 'de' (French for 'from').
'criminal' becomes 'fence' (I've seen this before).
'de'+'fence'='DEFENCE'
(Other definitions for defence that I've seen before include "Purpose of armed forces" , "Protection; justification" , "Armed forces' role" , "A means of protecting from attack" , "Resistance to attack" .)