Sudden blast son's taken in belly (4)
I believe the answer is:
gust
'sudden blast' is the definition.
(as in a gust of wind)
'son's taken in belly' is the wordplay.
'taken in' is an insertion indicator.
'belly' becomes 'gut' (informal term for the stomach or gut).
's' put within 'gut' is 'GUST'.
(Other definitions for gust that I've seen before include "Sudden blow of wind" , "Flurry" , "Squall" , "Blast of air" , "Burst of strong wind" .)