One side is insufficient for the whole game (3)

I believe the answer is:

leg

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'one side' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I don't see?

'insufficient for the whole game' is the wordplay.
'LEG' is hidden within the letters.
However, I'm uncertain how this is indicated.

'is' acts as a link.

Can you help me to learn more?

(Other definitions for leg that I've seen before include "prop" , "part of course" , "Stage (of race)" , "Limb; stage" , "Poultry portion" .)

I've seen this clue in the Evening Standard.

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