Seasonal wind of the Indian Ocean (7)
I believe the answer is:
monsoon
'seasonal wind of the indian ocean' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for monsoon that I've seen before include "Rainy season in southern Asia" , "Wet seasonal wind" , "Seasonal wind (south-west or north-east) of southern Asia" , "Seasonal Asian wind" , "Rainy period" .)