"Stormy" sea bird (6)
I believe the answer is:
petrel
'stormy sea bird' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for petrel that I've seen before include "Seabird (that may be stormy)" , "18's [BIRD]" , "Seabird that flies far from land" , "Mother Carey's chicken" , "Seabird sounds like fuel" .)