Green’s Dictionary of Slang

clinkers n.

[the noise]

1. chains and fetters worn by imprisoned felons.

[UK]B.E. Dict. Canting Crew n.p.: Clinkers c. the Irons Felons wear in Goals.
[UK]A. Smith Lives of Most Notorious Highway-men, etc. (1926) 204: Clinkers, the irons felons wear in gaol.
[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.
[UK]Flash Dict. in Sinks of London Laid Open.
[US]Matsell Vocabulum.
[US]Goldin et al. DAUL 45/2: Clinkers. Shackles, especially for fettering the ankles.

2. stairs [creaking stairs or the ‘clink’ of feet].

[UK]Marvel 12 Nov. 6: You’ll ’ave to pad the ’oof up the clinkers.

3. (US Und.) handcuffs.

[US]Trumble Sl. Dict. (1890).
[US]Monteleone Criminal Sl. (rev. edn).

4. (Ulster) the testicles [supposedly ‘clinking’ testicles].

[Ire](con. 1945) S. McAughtry Touch and Go 155: Show me your whanger and I’ll tell you what age you are by the number of wrinkles in your clinkers.