Right by a whisker (4)
I believe the answer is:
just
I believe this is a double definition.
'right' is the first definition.
(associated in meaning)
'by a whisker' is the second definition.
(I've seen this before)
(Other definitions for just that I've seen before include "Barely - equitable" , "Fair; a moment ago" , "Morally right" , "Quite" , "Fair and proper" .)