Stupid daughter getting behind (4)
I believe the answer is:
daft
'stupid' is the definition.
(thesaurus)
'daughter getting behind' is the wordplay.
'daughter' becomes 'd'.
'getting' means one lot of letters go next to another.
'behind' becomes 'aft' ('aft' can be a synonym of 'behind').
'd'+'aft'='DAFT'
(Other definitions for daft that I've seen before include "Informally silly or foolish" , "Potty" , "Informally silly or crazy" , "Half-witted" , "like a brush?" .)