So much French spirit causes outburst (7)
I believe the answer is:
tantrum
'outburst' is the definition.
(I've seen this before)
'so much french spirit' is the wordplay.
'so much french' becomes 'tant' (tant is french for so).
'spirit' becomes 'rum' (I've seen this before).
'tant'+'rum'='TANTRUM'
'causes' acts as a link.
(Other definitions for tantrum that I've seen before include "fit of bad temper" , "Wobbly" , "Childish outbreak of temper" , "Uncontrolled outburst of anger" , "Burst of rage" .)