Frankness (7)
'frankness' is the definition.
(synonyms)
This is all the clue.
(Other definitions for candour that I've seen before include "open)" , "show frankness" , "Forthrightness" , "Frankness, openness" , "telling it like it is" .)
(Other definitions for honesty that I've seen before include "Fairness" , "Plant; sincerity" , "that's easily cultivated" , "Candour" , "truth" .)