Conceal empty suitcase on island (7)
I believe the answer is:
secrete
'conceal' is the definition.
(I know that secrete is a type of conceal)
'empty suitcase on island' is the wordplay.
'empty' means to remove the middle letters.
'on' is a charade indicator (letters next to each other).
'island' becomes 'crete' (Greek island).
'suitcase' with its centre removed is 'se'.
'se'+'crete'='SECRETE'
(Other definitions for secrete that I've seen before include "Cache" , "Hide away" , "Hold and send out substance into the body as gland does" , "Hide - discharge" , "Place out of sight, hide" .)