Quite honestly (6)
I believe the answer is:
fairly
This clue is a double definition.
'quite' is the first definition.
(thesaurus)
'honestly' is the second definition.
(thesaurus)
(Other definitions for fairly that I've seen before include "Quite" , "Justly, without favouring one party" , "To a moderate degree" , "Moderately" , "In an evenhanded manner - somewhat" .)