Great hawk bearing west (5)
I believe the answer is:
swell
'great' is the definition.
(I know that great can be written as swell)
'hawk bearing west' is the wordplay.
'hawk' becomes 'sell' (hawk can mean to sell or trade).
'bearing' is an insertion indicator.
'west' becomes 'W' (abbreviation).
'sell' going around 'w' is 'SWELL'.
(Other definitions for swell that I've seen before include "Excellent! - become larger" , "Man of high social standing" , "Gentle sea movement" , "Dilate - jolly good!" , "Balloon - dandy" .)