Green’s Dictionary of Slang

a hideout; occas. attrib.

1937		E. Anderson Thieves Like Us (1999) 46: We got a good Hole-up in this joint.
1940		O. Strange Sudden Takes the Trail 166: It would take an Injun to discover that hole-up in the hills.
1952		Lait & Mortimer USA Confidential 169: This is the hole-up place for American mob boys.
1990		(con. early 1950s) J. Ellroy L.A. Confidential 124: Runs a hole-up for parole ’sconders.
2001		(con. 1964–8) J. Ellroy Cold Six Thousand 653: Bob Relyea had his hole-up. Bob had some shack near Phoenix.