Some of the grease we removed from the drain (5)
I believe the answer is:
sewer
'the drain' is the definition.
(sewer is a kind of drain)
'some of the grease we removed' is the wordplay.
'some of' says the answer is hidden in the clue.
'SEWER' can be found hidden inside 'grease we removed'.
'from' acts as a link.
(Other definitions for sewer that I've seen before include "One stitching - discharge channel" , "Conduit for carrying away waste matter" , "Channel to carry away waste water and matter" , "Main drain" , "Tailor" .)