Green’s Dictionary of Slang

1. a good meal.

1855		T. Haliburton Nature and Human Nature I 244: They talked of [...] taking a tuck-in at lunch.
1864, 1867, 1870		Hotten Sl. Dict. 262: Tuck in, or tuck out, a good meal.
1870		Hotten Sl. Dict.
1880		G.F. Northall ‘Momus’ Misc. 33: To enter a pastry cook’s shop, and have a good tuck in.
1888		‘Rolf Boldrewood’ Robbery Under Arms (1922) 80: He’d had a pretty good tuck-in himself.
1895		Coburg Leader (Vic.) 6 Apr. 4/3: Not content with having a good tuck-in on Saturday night, the water melon push stow away for the Sabbath also.
1898		Boy’s Own Paper 29 Oct. 68: I’ll stand you a tuck-in if you’ll help.
1902		J. Conrad Heart of Darkness 75: Why in the name of all the gnawing devils of hunger they didn’t go for us – they were thirty to five – and have a good tuck in for once, amazes me now when I think of it.
1916		Firefly 9 Dec. 1: I had a good tuck in and a nice warm in front of that roaring fire.
1916		‘Anzac’ On the Anzac Trail 9: By the wish of the men the evening meal was made the principal one; it was always a solid, hot tuck-in.
1922		Joyce Ulysses 358: Blown in from the bay [...] Always at home at dinnertime. Looks mangled out: had a good tuck in.
c.1930		(ref. to late 19C) N. Kimball Amer. Madam (1981) 105: After a good tuck-in at lunch, Zig would open the first two buttons on his pants.
1943		M. Harrison Reported Safe Arrival 48: You, if you were back in ‘civvy street’ [...] would you not begrudge a tuck-in to men who had long been denied.
1950		C. Harris Three-Ha’Pence to the Angel 43: All ’e’s interested in is a tuck-in [...] ’e finishes up in a posh restaurant place.
1966		P. White Solid Mandala (1976) 96: Aren’t you hungry? [...] I am! I’m looking forward to a good tuck-in.

2. a hearty eater.

1866

Bury & Norwich Post 15 May 2/6: He was always a jolly good tuck-in.