Seeds contributed to those French (7)
I believe the answer is:
lentils
'seeds' is the definition.
(I know this)
'contributed to those french' is the wordplay.
'contributed' becomes 'lent' ('lend' can be a synonym of 'contribute').
'to those french' becomes 'ils' ('those' in French).
'lent'+'ils'='LENTILS'
(Other definitions for lentils that I've seen before include "Pulse" , "Leguminous seeds for soup or stew" , "Protein-rich pulses" .)