God gets everyone a horse (5)
I believe the answer is:
allah
'god' is the definition.
(Arabic name for God)
'everyone a horse' is the wordplay.
'everyone' becomes 'all' (all people).
'horse' becomes 'H' (abbreviation as in horse power).
'all'+'a'+'h'='ALLAH'
'gets' acts as a link.
(Other definitions for allah that I've seen before include "Muslim and Arab name of God" , "God worshipped in 5 Across" , "God of the Muslims" , "God in Islam" , "God of the Arabs" .)