Small island bird’s beginning to disappear (4)
I believe the answer is:
inch
'small island' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for inch that I've seen before include "1/12 of foot" , "make slow progress" , "Rare bird follower" , "See 12" , "Creep towards < island" .)