Birds move round island slowly at first (7)
I believe the answer is:
budgies
'birds' is the definition.
(budgie is a kind of bird)
'move round island slowly at first' is the wordplay.
I cannot really understand how this works, but
'island' could be 'i' (geographical abbreviation) and 'i' is found in the answer.
'move' could be 'budge' (to budge is to move slightly) and 'budge' is located in the remaining letters.
A single letter 's' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for budgies that I've seen is " Small parakeets".)