Cruel base swaggering Three Musketeers' cry? (5,4)
I believe the answer is:
sacre bleu
'three musketeers' cry?' is the definition.
(the Three Musketeers spoke French)
'cruel base swaggering' is the wordplay.
'swaggering' is an anagram indicator.
'cruel'+'base'='cruelbase'
'cruelbase' with letters rearranged gives 'SACRE BLEU'.
(Other definitions for sacre bleu that I've seen before include "in Calais, an indication of exasperation" , "holy cow at Lourdes" , "Nice exclamation" .)