Spread includes old Spanish wine for ruler (9)
I believe the answer is:
potentate
'ruler' is the definition.
(potentate is a kind of ruler)
'spread includes old spanish wine' is the wordplay.
I cannot quite understand how this works, but
'old' could be 'o' (abbreviation as in OT - Old Testament) and 'o' is found within the answer.
'wine' could be 'tent' (type of Spanish wine) and 'tent' is found within the answer.
'spread' could be 'pate' (pate is a kind of spread) and 'pate' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for potentate that I've seen before include "authority" , "Powerful autocratic ruler" , "Mogul" , "A monarch or ruler" .)