Unctuous (4)
'unctuous' is the definition.
(I know that unctuous can be written as oily)
This is the entire clue.
(Other definitions for oily that I've seen before include "Smooth; like lubricant" , "Unpleasantly ingratiating" , "Greasy - obsequious" , "Viscous" , "Covered in lubricant" .)
'unctuous' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for greasy that I've seen before include "Sycophantic" , "Covered with fat" , "Oily in manner, covered with lubricant" , "Cheap 24" , "'Fatty, oily (6)'" .)