Cheese leaves nasty smear in vessel (8)
I believe the answer is:
parmesan
'cheese' is the definition.
(Parmesan is an example)
'nasty smear in vessel' is the wordplay.
'nasty' indicates an anagram.
'in' is an insertion indicator.
'vessel' becomes 'pan' (I have seen 'Shallow vessel ' mean 'pan' so perhaps 'vessel' could also mean 'pan').
'smear' with letters rearranged gives 'armes'.
'armes' placed into 'pan' is 'PARMESAN'.
'leaves' acts as a link.
(Other definitions for parmesan that I've seen before include "Italian cheese, often grated" , "Dry sharp-flavoured Italian cheese" , "that grates" , "Italian 8 across" , "Hard dry cheese, often grated" .)