Having bought, though about a quarter is on credit (6)
I believe the answer is:
Here is my best explanation:
'having' is the definition.
('own' can be a synonym of 'have')
'bought though about a quarter is on credit' is the wordplay.
I cannot really see how this works, but
'quarter' could be 'w' and 'w' is present in the answer.
'about' could be 'on' and 'on' is found in the leftover letters.
This may be the basis of clue (or it may be nonsense).
(Other definitions for owning that I've seen before include "Possessing", "Conceding - possession", "Having", "In legal possession of", "Being in possession or confessing", "Possesing" and "Admitting".)