Non-binary Lilliputian disputant? (8)

I believe the answer is:

bigender

I'm a little stuck... Click here to teach me more about this clue!

'non-binary' is the definition.
(I know that bigender is a type of non-binary)

I cannot understand how the rest of the clue works.

I've seen this clue in The Independent.

Want a hint initially instead of a full solution? Install my app