Can endure unusual stamina (9)
I believe the answer is:
endurance
'stamina' is the definition.
(I've seen this before)
'can endure unusual' is the wordplay.
'unusual' indicates an anagram.
'can'+'endure'='canendure'
'canendure' anagrammed gives 'ENDURANCE'.
(Other definitions for endurance that I've seen before include "Stamina" , "ship bound for the Antarctic" , "Fortitude" , "Polar ship" , "Lasting quality" .)