I'll add my welcome, Wispy. Here's part of what C.K.'s link has:

Wick"et (?), n. [OE. wiket, OF. wiket, guichet, F. quichet; probably of Scand. origin; cf. Icel. vk a small creek, inlet, bay, vik a corner.]
1. A small gate or door, especially one forming part of, or placed near, a larger door or gate; a narrow opening or entrance cut in or beside a door or gate, or the door which is used to close such entrance or aperture. Piers Plowman. Heaven's wicket." Milton.

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Without seeing the actual context, it's hard for me to tell what the author is describing. Possibly she is meaning a
half-door, or part of a countertop that lifts up, to allow
restricted access to where the betting money is taken in.