Old Sulawesi star eats crusts (7)
I believe the answer is:
celebes
'old sulawesi' is the definition.
The definition suggests a singular noun which matches the answer.
'star eats crusts' is the wordplay.
'star' becomes 'celeb' (I've seen this in another clue).
'eats crusts' becomes 'es' (I can't justify this - if you can you should give a lot more credence to this answer).
'celeb'+'es'='CELEBES'
Can you help me to learn more?
(Other definitions for celebes that I've seen before include "English name for Sulawesi" , "Pacific island" , "Anglicised spelling of Sulawesi (Indonesia)" .)