Green’s Dictionary of Slang

1. to kick, to trip up.

1980		J. McClure Spike Island (1981) 37: There’s this buck wellying shite out of the wings of the car!
1989		J. Morton Lowspeak.
1998		Guardian Sport 25 Sept. 16: A heavy ball stops you trying to welly it.
2000		J. Hawes Dead Long Enough 218: The guy’s holding some piece of scaffolding or whatever, and wellying the shit out of the side of the van.

2. to beat up, to assault.

2003		N. Griffiths Stump 37: Let’s go an welly this one-armed cunt.
2012		J. Fagan Panopticon (2013) 21: There’s banging out on the landing [...] he’s really wellying that balcony.