Green’s Dictionary of Slang

clank n.

also clanker, clink
[echoic; i.e. the tankard, plate or dollar hitting a table]

1. (UK Und.) a silver tankard; thus rum clank, a double tankard.

[UK]B.E. Dict. Canting Crew n.p.: Clank c. a silver tankard.
[UK]A. Smith Lives of Most Notorious Highway-men, etc. (1926) 204: Clank, a silver tankard.
[UK]New Canting Dict.
[UK]Bailey Universal Etym. Eng. Dict.
[UK]B.M. Carew Life and Adventures.
[UK]J. Poulter Discoveries (1774) 42: I’m a Sneak for Chinks [sic] and Feeders; I’m a Thief for Tankards or Spoons.
[UK](con. 1710–25) Tyburn Chronicle II in Groom (1999) xxix: A Clank A Tankard.
[UK]G. Parker View of Society II 176: Clink Rig. Stealing silver tankards, pints, &c. Landlords too readily trust strangers into rooms where they deposit plate.
[UK]H.T. Potter New Dict. Cant (1795) n.p.: clank or clankers silver tankards or cups.
[UK]G. Andrewes Dict. Sl. and Cant [as cit. a.1790].
[UK]Lex. Balatronicum.
[UK]‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 51: Clank — silver vessels, spoons, candlesticks.
[UK]Disraeli Venetia I 153: Tip me the clank like a dimber mort, as you are.
[UK]Flash Dict. in Sinks of London Laid Open.
[UK]Duncombe New and Improved Flash Dict.
[US]Matsell Vocabulum 19: clankers Silver vessels.
[US]Trumble Sl. Dict. (1890).

2. (UK Und.) a silver plate.

[UK]G. Parker Life’s Painter 138: The melting pot receiver, proved his selling the clink to him (naps the bib) and that’s what did him over.

3. (US) a silver dollar.

[US]C. Samolar ‘Argot of the Vagabond’ in AS II:9 390/1: A dollar, a clanker or slug.

In compounds

clank-napper (n.) [napper n.1 (1)]

a thief who specializes in stealing silver plate.

[UK]B.E. Dict. Canting Crew n.p.: Clank-napper, c. a Silver-tankard Stealer.
[UK]A. Smith Lives of Most Notorious Highway-men, etc. (1926) 204: Clank-knapper, a silver tankard stealer.
[UK]New Canting Dict.
[UK]Bailey Universal Etym. Eng. Dict.
[UK]Grose Classical Dict. of the Vulgar Tongue.
[UK]Lex. Balatronicum.
[UK]Egan Grose’s Classical Dict. of the Vulgar Tongue.