Occupant of bed regrets you're taking it back (6)
I believe the answer is:
oyster
'occupant of bed' is the definition.
'regrets you're taking it back' is the wordplay.
'taking it' says the answer is hidden in the clue.
'back' says the letters should be written backwards.
'retsyo' is hidden in the letters of 'regrets youre'.
'retsyo' back-to-front is 'OYSTER'.
(Other definitions for oyster that I've seen before include "Pearl container?" , "Pearl-making mollusc" , "Pearl-bearing sea creature" , "Means to cross London" , "aphrodisiac?" .)