Frenchman adopting say, daughter, went back (7)
I believe the answer is:
reneged
'went back' is the definition.
(I've seen this before)
'frenchman adopting say daughter' is the wordplay.
'frenchman' becomes 'rene' (common French name).
'adopting' is an insertion indicator.
'say' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'daughter' becomes 'd' (genealogical abbreviation).
'rene' going around 'eg' is 'renege'.
'renege'+'d'='RENEGED'
(Other definitions for reneged that I've seen before include "Did Welsh" , "Go back on, or revoke in card game" , "Went back on (a promise)" , "Was a rat" , "Broke a promise" .)