Leaves a supplier of spares (5,7)
I believe the answer is:
parts company
'leaves' is the definition.
'a supplier of spares' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
'of' could be 'o' and 'o' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for parts company that I've seen before include "Splits up" , "Member of a group goes their own way" , "firm producing vehicle components?" .)