Eleven of Italy’s fifty islands — rest over to the west (6)
I believe the answer is:
napoli
'eleven of italy's' is the definition.
The definition suggests a singular noun which matches the answer.
'fifty islands rest over to the west' is the wordplay.
I cannot really understand how this works, but
'fifty' could be 'li' (I've seen this in other clues) and 'li' is located in the answer.
'rest' could be 'nap' (I've seen this in another clue) and 'nap' is found within the answer.
'over' could be 'o' (cricket abbreviation) and 'o' is found within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for napoli that I've seen before include "Italian name for Naples" , "Italian city" , "Mediterranean city" , "Decline" .)