Cover staff back after a lot of resentment (7)
I believe the answer is:
envelop
'cover' is the definition.
(enveloping is a kind of covering)
'staff back after a lot of resentment' is the wordplay.
'staff' becomes 'pole' (both can mean a stick).
'back' says the letters should be written in reverse.
'after' is a charade indicator (letters next to each other).
'a lot of' means to remove the last letter (a lot of but not all of the word).
'resentment' becomes 'envy' (envy is a kind of resentment).
'pole' reversed gives 'elop'.
'envy' with its last letter taken off is 'env'.
'elop' put after 'env' is 'ENVELOP'.
(Other definitions for envelop that I've seen before include "Enclose" , "Enfold - surround" , "Wrap around completely" , "Cover by wrapping" , "Wrap up, cover on all sides" .)