Full Idea
Metaphysics Z.3, often read as denying that matter is a substance, can more plausibly be interpreted as claiming that matter cannot be the only and not a first-rank substance.
Gist of Idea
Aristotle says matter is a lesser substance, rather than wholly denying that it is a substance
Source
report of Aristotle (Metaphysics [c.324 BCE], matter) by Joan Kung - Aristotle on Essence and Explanation VI
Book Reference
-: 'Philosophical Studies' [-], p.376
A Reaction
This certainly sounds a more plausible view, and in modern understanding some kind of elemental matter is our best candidate for what could be meant by 'substance'. Perhaps the 'fields' of modern physics play that role.