Green’s Dictionary of Slang

1. the number six.

1937		Eve. News (London) 2 July in DSUE (1984).
a.1945		L. Payne private coll. n.p.: 6 Tom Mix.
1960		J. Franklyn Dict. of Rhy. Sl.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1981		P. Wright Cockney Dialect and Sl. 109: 6 = Tom Mix.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.
2011		Spitalfields Life 18 Nov. 🌐 And he said to me, Tom Mix, which is rhyming slang. What’s Tom Mix?

2. a problem, a predicament [SE fix, a dilemma].

1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1977		D. Powis Signs of Crime 205: Tom Mix Predicament (fix): ‘She’s in a bit of a tom mix.’.
2002		D. Shaw ‘Dead Beard’ at www.asstr.org 🌐 But while she’s screaming I’m reaming and getting in even deeper, and I bet she wondering how she ever got herself in such a tom mix.

3. an injection of heroin [fix n.³ (1)].

1971

E.E. Landy Underground Dict. (1972).