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 really understand how this works, but
'old' could be 'o' (abbreviation as in OT - Old Testament) and 'o' is found in the answer.
'wine' could be 'tent' (type of Spanish wine) and 'tent' is found in the answer.
'spread' could be 'pate' (pate is a kind of spread) and 'pate' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'for' acts as a 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" .)