Former lover brings charm to departure (4)
I believe the answer is:
exit
'departure' is the definition.
(I know that departure can be written as exit)
'former lover brings charm' is the wordplay.
I cannot really see how this works, but
'former' could be 'ex' (prefix meaning former or onetime) and 'ex' is found in the answer.
'charm' could be 'it' (intangible human quality: 'she has it') and 'it' is located in the answer.
No letters remain.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for exit that I've seen before include "Way to leave" , "Depart" , "Outlet" , "Escape route?" , "Player's departure" .)