Fruit with really cheesy covering (6)
I believe the answer is:
lychee
'fruit' is the definition.
(lychee is a kind of fruit)
'with really cheesy covering' is the wordplay.
'with' indicates the answer is hidden within the clue.
'LYCHEE' can be found hidden inside 'really cheesy covering'.
(Other definitions for lychee that I've seen before include "Litchi" , "Oriental fruit" , "Large-stoned fruit" , "Juicy Chinese fruit" , "White-fleshed fruit" .)