Possessed by a slavish admirer (3)
I believe the answer is:
had
'possessed' is the definition.
(to have something is to possess it)
'by a slavish admirer' is the wordplay.
'by a' indicates the answer is hidden within the clue.
'HAD' can be found hidden inside 'slavish admirer'.
(Other definitions for had that I've seen before include "Was bound to be - caught" , "Taken in" , "Did trick" , "Owned in the past" , "kept" .)