A cardinal virtue (4)
I believe the answer is:
hope
'a cardinal virtue' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hope that I've seen before include "Positive expectation" , "Bob --, US comedian" , "Cross your fingers" , "It goes with faith and charity" , "The last thing in Pandora's Box" .)