Is the second-born child with the French girl? (8)
I believe the answer is:
isabella
'girl?' is the definition.
(girl's name)
'is the second-born child with the french' is the wordplay.
'the second-born child' becomes 'Abel' (second child born in the Bible).
'with' says to put letters next to each other.
'the french' becomes 'la' (one of the French words for 'the').
'is'+'abel'+'la'='ISABELLA'
(Other definitions for isabella that I've seen before include "Name of two Spanish queens" , "Spanish queen who was patron of Christopher Columbus" , "Spanish queen who was patroness to Columbus" , "Henry VIII's first mother-in-law" , "sludgy colour" .)