Green’s Dictionary of Slang

1. a crafty person.

1674		Head Canting Academy (2nd edn).
c.1698		B.E. Dict. Canting Crew.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1793		‘Bonie Mary’ in Burns Merry Muses of Caledonia (1965) 51: And was nae Wattie a Clinker, / He m—w’d frae the Queen to the the tinkler.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1905		J.W. Carr ‘Words from Northwest Arkansas’ in DN III:i 75: clinker, n. [...] 2. A cheat. ‘Our boarding-house mistress is a clinker’.

2. a lie, a deception.

1832

Satirist (London) 18 Nov. 376/2: The coal whipper represented the charge, as an attempt to blacken his fair fame, and said that all the lady had stated, was a regular clinker.