Green’s Dictionary of Slang

to confuse, to entangle, to impede.

1927		(con. 1914–18) L. Nason Three Lights from a Match 60: How did we get snarled up with the Germans?
1941		Detroit Free Press (MI) 22 Nov. 5/2: He snarls up defence. He snarls up the national leaders who try to deal with him.
1956		J. Curtis Look Long Upon a Monkey 79: She was snarled up and needed his help.
1964		Dly Mirror (London) 27 Feb. 10/4: The public [...] had done its usual quota to snarl up the works.
1974		Newcastle Eve. Chron. 25 Jan. 15/5: The shortages could snarl up the building industry.
1992		D. Jarman diary 23 July Smiling in Slow Motion (2000) 177: [of traffic] Snarled up at Hyde Park corner, everyone at cross purposes.