Chaperone expected to accompany girl over (6)
I believe the answer is:
duenna
'chaperone' is the definition.
(duenna is a kind of chaperone)
'expected to accompany girl over' is the wordplay.
'expected' becomes 'due' (I've seen this before).
'to accompany' is a charade indicator (letters next to each other).
'girl' becomes 'ann' (**).
'over' shows that the letters should be reversed in order.
'ann' reversed gives 'nna'.
'due'+'nna'='DUENNA'
(Other definitions for duenna that I've seen before include "mature escort" , "governess in Spain" , "Governess, chaperone" , "Spanish chaperon or governess" , "Iberian chaperone" .)