Traveller in Russian plane heading towards storm (7)
I believe the answer is:
'traveller' is the definition.
(I know that migrant is a type of traveller)
'russian plane heading towards storm' is the wordplay.
'russian plane' becomes 'MiG' (MiG is a Russian aircraft manufacturer).
'heading towards' says to put letters next to each other.
'storm' becomes 'rant' (both can mean to rage).
'in' acts as a link.
(Other definitions for migrant that I've seen before include "relocating" , "Person moving countries" , "One travelling to find work" , "Ring mat (anag.)" , "Changing habitat (bird)" .)