Forms to be filled at a general election (5,5)

I believe the answer is:

empty seats

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'a general election' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'forms to be filled at' is the wordplay.
I cannot quite see how this works, but
'at' is present in the answer.
This explanation may well be incorrect...

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I've seen this clue in The Globe and Mail.

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