Not exactly sixes, nevertheless boundaries (5)
I believe the answer is:
sides
'boundaries' is the definition.
(side is a kind of boundary)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for sides that I've seen before include "Borders?" , "Flanks, or opposing teams" , "Takes the part of someone in a dispute" , "Faces" , "Sports teams" .)