Unrivalled but not yet married (9)
I believe the answer is:
matchless
'unrivalled' is the definition.
(synonyms)
'not yet married' is the wordplay.
I cannot really see how this works, but
'not' could be 'less' (I've seen this in other clues) and 'less' is located in the answer.
'married' could be 'm' (abbreviation, e.g. in genealogy) and 'm' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'but' is the link.
Can you help me to learn more?
(Other definitions for matchless that I've seen before include "Without peer, nonpariel" , "Unparalleled" , "Like the top" , "Unbeatable" , "Unequalled" .)