Some began nettling seabird (6)
I believe the answer is:
gannet
'seabird' is the definition.
(type of seabird)
'some began nettling' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'GANNET' is hidden within 'began nettling'.
(Other definitions for gannet that I've seen before include "Gluttonous type" , "Ten nag the sea-baird" , "Solan goose was this bird's former name" , "Large seabird noted for its plunging dives for fish" , "A large diving sea-bird" .)