This bird left Noah's ship (4)
I believe the answer is:
lark
'this bird' is the definition.
(lark is a kind of bird)
'left noah's ship' is the wordplay.
'left' becomes 'l' (common abbreviation).
'noah's ship' becomes 'ark' (I've seen this before).
'l'+'ark'='LARK'
(Other definitions for lark that I've seen before include "Mess about" , "High-flying songbird" , "Bit of fun - early-rising bird?" , "in-flight performer" , "Flighty type" .)