Still on level terms (4)
I believe the answer is:
even
I believe this clue is a double definition.
'still' is the first definition.
(I know that still can be written as even)
'on level terms' is the second definition.
(I've seen this before)
(Other definitions for even that I've seen before include "on level terms" , "Iron - uniform - flat" , "Flattened" , "Unvarying" , "Placid - not easily angered" .)