2 Upon a ravenous wolf, and still did chaw
still > ever, continually chaw > chew, champ upon; fig.: ruminate, brood upon
3 Between his cankered teeth a venomous toad,
cankered > ulcerated
4 That all the poison ran about his chaw;
That > [So that] chaw > jaw, jaws
5 But inwardly he chawed his own maw
maw > stomach
6 At neighbour's wealth, that made him ever sad;
neighbour > [specifically, perhaps, Avarice] wealth > wealth; or: well-being