Return engagement (8)
I believe the answer is:
interest
This clue is a double definition.
'return' is the first definition.
(thesaurus)
'engagement' is the second definition.
(thesaurus)
(Other definitions for interest that I've seen before include "intrigue" , "Money paid on a loan" , "Deep concern - premium paid for use of money" , "Share in an undertaking" , "Money made by or paid for money" .)