Hide some covers on an island (7)
I believe the answer is:
secrete
'hide' is the definition.
(I know that secrete is a more specific form of the action hide)
'some covers on an island' is the wordplay.
'covers' means to remove the middle letters (I've seen 'covering' mean this (the letters which cover the word are used)).
'on' is a charade indicator (letters next to each other).
'an island' becomes 'crete' (Greek island).
'some' with its middle removed is 'se'.
'se'+'crete'='SECRETE'
(Other definitions for secrete that I've seen before include "Hide - discharge" , "Hide; as gland does" , "Hide away" , "harbour" , "squirrel" .)