A way to travel on horseback? (7)
I believe the answer is:
astride
'on horseback?' is the definition.
(I've seen this before)
'a way to travel' is the wordplay.
'way' becomes 'st'.
'to travel' becomes 'ride' (riding is a kind of travelling**).
'a'+'st'+'ride'='ASTRIDE'
(Other definitions for astride that I've seen before include "On the back of" , "Not side saddle" , "On top of" , "Passing across" , "Standing over amid tirades" .)