Release the French aristocrat (3,3)
I believe the answer is:
let off
'release' is the definition.
(thesaurus)
'the french aristocrat' is the wordplay.
'the french' becomes 'le' ('the' in French).
'aristocrat' becomes 'toff' (toff can mean an upper-class person).
'le'+'toff'='LET OFF'
(Other definitions for let off that I've seen before include "Excuse or release of" , "Release by exploding - pardon" , "Fire escape" , "given a reprieve" , "Go easy on" .)