Wines cultivated for strength (5)
I believe the answer is:
sinew
'for strength' is the definition.
(sinew is a kind of strength)
'wines cultivated' is the wordplay.
'cultivated' is an anagram indicator.
'wines' with letters rearranged gives 'SINEW'.
(Other definitions for sinew that I've seen before include "Tough connective tissue" , "Force" , "fibre" , "Strength; tendon" , "power source" .)