On the square (6)
I believe the answer is:
honest
'on the square' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for honest that I've seen before include "Truthful in manner" , "Uncorrupt - open - genuine" , "Fair and square" , "Honorable, true" , "Truthful and dependable" .)