OK – let’s try to see what we know:
It is a belt but it is not worn as such and is not an item of clothing. It is a part of a larger whole, but can be made separately (a replaceable part?) It may be made of A, V or M and is always ‘sort of’ the same shape although the size can vary. If Animal this could be leather. Manufactured although not necessarily by machine. Irg has made one. It is functional rather than decorative. It has some 'sort of' connection with 'attaching' but not of one thing to another (still slightly confused by that). The answer is one word plus the indefinite article, but this could exist in the plural. It is not normally elastic (although that is not impossible). It does not normally contain or hold other things (bandolier, tool belt)
It is not: a buckle or fastener (applause), garters, dog tag or leash, safety harness, seat belt, handcuffs or other bondage gear, a conveyor belt or a number of other things excluded by the things we know.

Raak] Is it a drive-belt? YES! (Specifically a fanbelt, but that's good enough).Apologies for the 'connecting one thing to another' answer, which I think was wrong now - I was trying to get at the idea of it being internal. And the answer to Dujon's tool-belts question was misleading, as I didn't read it properly. Not one of my better ones. One baton improvised from tights handed over to Raak.

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That was unexpected. Hmm... MINERAL and ANIMAL, with ABSTRACT connections.