Owns a number - so hurry! (6)
I believe the answer is:
hasten
'hurry' is the definition.
(I know that hurry can be written as hasten)
'owns a number' is the wordplay.
'owns' becomes 'has' ('have' can be a synonym of 'own').
'a number' becomes 'ten' (ten is a number).
'has'+'ten'='HASTEN'
'so' acts as a link.
(Other definitions for hasten that I've seen before include "Be quick to do something" , "Travel with expedition" , "Athens (anag.)" , "Step up" , "Make faster" .)