Returning in encore, Rihanna's an engaging sort (5)
I believe the answer is:
hirer
'engaging sort' is the definition.
(I've seen this in another clue)
'returning in encore rihanna's' is the wordplay.
'returning' says the letters should be written in reverse.
'in' indicates a hidden word.
'rerih' can be found hidden inside 'encore rihannas'.
'rerih' reversed gives 'HIRER'.
'an' acts as a link.
(Other definitions for hirer that I've seen before include "Person who takes on workers" , "He purchases tempory use of something" , "He'll pay for using" , "One who lets out" , "One paying for temporary use (of something)" .)