Disappointing outcome that must hold little girl back (2,3)
I believe the answer is:
no joy
'disappointing outcome' is the definition.
('no joy' is said after a disappointing outcome)
'that must hold little girl back' is the wordplay.
'that' becomes 'yon' (archaic term meaning 'that').
'must hold' is an insertion indicator.
'little girl' becomes 'jo' (short for Josephine).
'back' says the letters should be written in reverse.
'yon' enclosing 'jo' is 'yojon'.
'yojon' reversed gives 'NO JOY'.
(Other definitions for no joy that I've seen before include "Unsuccessful (colloq.)" , "lack of success" .)