Seabird almost short of breath? (6)
I believe the answer is:
puffin
'seabird' is the definition.
(I know that puffin is a type of seabird)
'almost short of breath?' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'short of breath?' becomes 'puffing'.
'puffing' with its last letter taken away is 'PUFFIN'.
(Other definitions for puffin that I've seen before include "Bird with large beak" , "Bright-billed auk" , "Large-billed sea bird" , "Bird with colourful beak" , "Seabird with a colourful bill" .)