Topped, stewed and covered with greasy stuff (5)
I believe the answer is:
oiled
'covered with greasy stuff' is the definition.
'oiled' can be an answer for 'covered' (oiling is a kind of covering). I'm not certain of the 'with greasy stuff' bit.
'topped stewed' is the wordplay.
'topped' means to remove the first letter (to top something is to remove its top).
'stewed' becomes 'boiled' (synonyms).
'boiled' with its first letter taken away is 'OILED'.
'and' is the link.
Can you help me to learn more?
(Other definitions for oiled that I've seen before include "running smoothly?" , "protected from rust?" , "Anointed" , "as silk may be" , "Greased; drunk" .)