Lover once wholly transfixed by island of great beauty (9)
I believe the answer is:
exquisite
'of great beauty' is the definition.
'lover once wholly transfixed by island' is the wordplay.
'lover once' becomes 'ex'.
'wholly' becomes 'quite'.
'transfixed by' is an insertion indicator.
'island' becomes 'is'.
'quite' placed around 'is' is 'quisite'.
'ex'+'quisite'='EXQUISITE'
(Other definitions for exquisite that I've seen before include "Of the highest excellence" , "Having special or rare beauty" , "Extremely beautiful" , "delightful?" , "Sharp" .)