Bird makes moves to leave boat (9)
I believe the answer is:
disembark
'leave boat' is the definition.
'bird makes moves' is the wordplay.
'moves' indicates an anagram.
'bird'+'makes'='birdmakes'
'birdmakes' with letters rearranged gives 'DISEMBARK'.
'to' is the link.
(Other definitions for disembark that I've seen before include "Go ashore" , "Step on dry land" , "to set oneself apart from trader, say" , "Get off" .)