Plane's speed cuts journeys to new destination (8)

'journeys to new destination' is the definition.
(to migrate is to journey elsewhere)

'plane's speed cuts' is the wordplay.
'plane's' becomes 'mig's' (fighter jet produced by Russian company MiG).
'speed' becomes 'rate' (the speed at which something happens).
'cuts' is an insertion indicator (a group of letters 'cuts' into another word).
'migs' going around 'rate' is 'MIGRATES'.