Green’s Dictionary of Slang

1. (W.I./UK black teen) the main street or area, the main area of attraction or focus of activities.

1992		V. Headley Yardie 45: The ‘front line’, the main street where all the wheeling and dealing happpened in this area. [Ibid.] 49: He would surely find someone from their team on the line.
1994		I. Welsh ‘Stoke Newington Blues’ in Acid House 36: I recognised a couple of black guys from the Line, at Sandringham Road.
2000		Observer Rev. 13 Feb. 4: Nearby is Sandringham Road, the old ‘front line’, where I spent years dealing. [Ibid.] Now the ‘front’ is a residential street like any other.
2001		(con. 1981) A. Wheatle East of Acre Lane 38: I’m going up de Line, try an’ sell some herb.

2. (UK black) that area of a city where the black community is most likely to clash with the forces of white law and order, e.g. All Saints Road, Notting Hill, Railton Road, Brixton etc.

1999		N. Cohn Yes We have No 222: For the next three years, he was out on the frontline, seven days a week.
2005		Roll Deep ‘Remember the Days’ 🎵 I was on front line before I used a Bic razor.
2008		A. Wheatle Dirty South 79: He was [...] selling weed on the front line. He was a hustler.

3. (Aus.) the leading edge oif urban gentrifdication, replacing the working class by the fashionable middle.

2021

Betoota-isms 220: The Front Line [...] 2. A collection of suburbs north of the city of Melbourne, famous as the birthplace of oat-based coffee orders, fixie bicycles and the displacement of housing commission residents.