Green’s Dictionary of Slang

teazer of (the) catgut n.

a violinist, a fiddler.

1821		Egan Life in London (1869) 321: Lascars, blacks, jack tars, coal-heavers [...] were all jigging together, provided the teazer of the catgut was not bilked of his duce.
1835		G. Kent Modern Flash Dict. 33: Teazer of catgut – a fiddler.
1848		Flash Dict. in Sinks of London Laid Open [as cit. 1835].