Like a revolution in space travel (7)
I believe the answer is:
orbital
'like a revolution in space travel' is the definition.
(relating to an orbit)
'a revolution in space travel' is the wordplay.
'a revolution' becomes 'orbit' (orbit is a kind of revolution).
'in space travel' becomes 'al' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'orbit'+'al'='ORBITAL'
(Other definitions for orbital that I've seen before include "Gyratory" , "(Of a road) going around a town" , "going round the city" , "kind of motorway" , "Revolutionary" .)