grit, v.² — Green’s Dictionary of Slang

grit v.²

also grit it

[SAmE grits, coarse oatmeal widely eaten in Southern US]

(US black/campus) to eat; thus gritting place n., a restaurant.

1966		Current Sl. I:3 3/2: Grit it, v. To eat.
1967		P. Thomas Down These Mean Streets (1970) 186: I just stood outside that greasy grittin’ place that served two kinda menus. [Ibid.] 300: Something you gritted, eh?
1971		H.E. Roberts Third Ear n.p.: grit v. to eat.
1995		L. Stavsky et al. A2Z.