Personnel absorbed by unlikely subject (6)
I believe the answer is:
thrall
'subject' is the definition.
(thesaurus)
'personnel absorbed by unlikely' is the wordplay.
'personnel' becomes 'HR' (Human Resources).
'absorbed by' indicates putting letters inside.
'unlikely' becomes 'tall' (as in a tall tale).
'hr' going inside 'tall' is 'THRALL'.
(Other definitions for thrall that I've seen before include "Slave, servant, captive" , "Slave(ry)" , "State of subservience" , "subjection" , "State of servitude" .)