Green’s Dictionary of Slang

1. (US) a musical discord, a fluffed note.

1933		W. Winchell On Broadway 11 Nov. [synd. col.] 2/2: Add Slanguage [...] A clinker is a sour note.
1940		Esquire May 202: In the Crosby band ‘clinkers’ fall on deaf ears.
1951		Kerouac On the Road (The Orig. Scroll) (2007) 337: See him grow worried when he blows a clinker.
1958		Hughes & Bontemps Book of Negro Folklore 482: clinker: A sour note in music. The trumpet hit a clinker.
1971		(con. 1910s) G.M. Foster Pops Foster 112: When we hit a clinker she’d mark it down. Then the Streckfus people would make us do it right. We’d call the clinkers ‘Blue Notes’.

2. a second-rate, worthless person.

1951		S. Lewis World So Wide 166: This fellow is a clinker.
1961		R.A. Norton Through Beatnik Eyeballs 13: I got to admit it, I’m a clinker from way out, strictly heading for nowhere.

3. something second-rate, inferior, esp. a performance.

1950		Sat. Eve. Post 15 July 126: Almost all the 24 films [...] have been real clinkers [W&F].
1969		P. Theroux Murder in Mount Holly (1999) 87: Think you can do that? Or have I got a real clinker in my platoon?
1978		L. Kramer Faggots 116: A foot-stomping clinker of completely non-urgent intensity.
1999		Observer 15 Aug. 23: The last fifteen years have mixed hits like Bugsy with clinkers like Ishtar.

4. (US) a problem, a difficulty.

1959		Mad mag. Dec. 46: A Rock ’n’ Roll singer has accidentally hit a clinker ... and pronounced a real understandable English word.
1961		Metronome Feb. 20: This ingenuous belief that Louis Armstrong can smile away the egregious clinkers in our foreign policy is akin to having Frank Sinatra do a policy paper on Algeria.
1979		E. Torres After Hours 172: He hit a couple of clinkers at the end.