Strength of unusual wines (5)
I believe the answer is:
sinew
'strength' is the definition.
(sinew is a kind of strength)
'unusual wines' is the wordplay.
'unusual' indicates anagramming the letters.
'wines' anagrammed gives 'SINEW'.
'of' is the link.
(Other definitions for sinew that I've seen before include "Tough material" , "power source" , "Strength; tendon" , "Force" , "Tough connective tissue" .)