Daughter, leaving study ahead of boys, makes excuses (7)
I believe the answer is:
reasons
'excuses' is the definition.
(I've seen this before)
'daughter leaving study ahead of boys' is the wordplay.
'daughter' becomes 'd'.
'leaving' is a deletion indicator.
'study' becomes 'read' ('read' can be a synonym of 'study').
'ahead of' says to put letters next to each other (I've seen this in other clues).
'boys' becomes 'sons' ('son' can be a synonym of 'boy').
'read' with 'd' taken away is 'rea'.
'rea'+'sons'='REASONS'
'makes' acts as a link.
(Other definitions for reasons that I've seen before include "Motives, explanations" , "excuses" , "Debates; thinks out" , "Justifications or motives" , "Rationalises" .)