Honourable, sincere (6)
I believe the answer is:
honest
I believe this is a double definition.
'honourable' is the first definition.
(associated in meaning)
'sincere' is the second definition.
(similar in meaning)
(Other definitions for honest that I've seen before include "Trustworthy or candid" , "Free of deceit and lies - truly!" , "Objective mediator" , "Truthful and dependable" , "Without dissimulation or guile" .)