Wasted away in huge island base (10)
I believe the answer is:
languished
'wasted away' is the definition.
('languish' can be a synonym of 'waste away')
'huge island base' is the wordplay.
'base' indicates anagramming the letters (base can mean impure or corrupt).
'huge'+'island'='hugeisland'
'hugeisland' with letters rearranged gives 'LANGUISHED'.
'in' is the link.
(Other definitions for languished that I've seen before include "Grew weak or feeble" , "Pined; lay neglected" , "Flagged" .)