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) and 'o' is located in the answer.
'wine' could be 'tent' (type of Spanish wine) and 'tent' is present in the answer.
'spread' could be 'pate' (pate is a kind of spread) and 'pate' is found in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'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" .)