The French yell and make a sudden attack (4,3)
I believe the answer is:
lash out
'attack' is the definition.
(I've seen this before)
'the french yell' is the wordplay.
'the french' becomes 'la' (one of the French words for 'the').
'yell' becomes 'shout' (synonyms).
'la'+'shout'='LASH OUT'
'and make a sudden' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for lash out that I've seen before include "unprovoked attack" , "Spend lots" , "React violently" , "Vigorously attack" , "Strike (or spend) wildly" .)