Slowly cooking peeled fruit (6)
I believe the answer is:
raisin
'fruit' is the definition.
(raisin is a kind of fruit)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for raisin that I've seen before include "Partially dried grape" , "Dried 18" , "Dried fruit" , "Fruit for the Christmas cake" , "Dried grape used in cakes" .)