Girl’s prayers captivating me on return (8)
I believe the answer is:
rosemary
'girl's' is the definition.
'prayers captivating me on return' is the wordplay.
'prayers' becomes 'rosary' (I've seen this before).
'captivating' is an insertion indicator (I've seen this in other clues).
'on return' says the letters should be written backwards.
'me' backwards is 'em'.
'rosary' placed around 'em' is 'ROSEMARY'.
(Other definitions for rosemary that I've seen before include "Aromatic herb" , "Plant" , "Helps one to remember" , "that could be useful in the kitchen" , "Fragrant evergreen shrub and herb" .)