Green’s Dictionary of Slang

1. to provide, to serve up.

1833		Satirist (London) 21 Apr. 549/3: ‘I have hashed up a conundrum, Jelf,’ said Cumberland.
1883		Gringo and Greaser 1 Sepp. 2/1: If we can find some other philanthropist who will kindly hash, beer and sleep us, we’ll be there [DA].
1891		N&Q Ser. 7 XII 22 Aug. 144: [...] Earle [...] would [i.e. not] have spoken thus of a thing hashed up by a hard-headed pedant, however able, such as Gauden [F&H].
2000		M. Collins Keepers of Truth 6: All I’m left with is creating postscripts to a dead town that I hash out in full-page spreads.

2. to ruin, to spoil, thus unhash, to disentangle, to improve [abbr. make a hash of].

1896		Hants. Teleg. 14 Nov. n.p.: He mustn’t hash the piece.
1907		Sun (NY) 24 Feb. 8/3: I ought to be in California making nod bets [...] but somebody crossed their fingers on me last season, and that hashed it.
1929		D. Hammett Red Harvest (1965) 123: I was making one of my favorite complaints--that newspapers were good for nothing except to hash things up so nobody could unhash them.

3. to work as a waiter/waitress in a café.

1899–1900		C.L. Cullen Tales of the Ex-Tanks 93: I’d been hashing it for a couple of weeks, saving every dollar.
1920		R.J. Fry Salvation of Jemmy Sl. I i: Heck! Sometimes I wish I was back [...] hashin’ out hamburgers.
1932		J.A. Shidler ‘More Stanford Expressions’ in AS VII No 6 437: To ‘hash’ is to earn one’s board by serving meals.
1975		G. Underwood ‘Razorback Sl.’ in AS L No 1/2 60: hashvi 1: Wait tables or serve food, usually as a part-time job.