How do I solve 28 across in Times Cryptic 29574?

Question

Accepted Answer

28 across reads "Length of timber that could make a cube" (3-2-4 letters); the answer is TWO-BY-FOUR. It's a double-definition clue: two separate definitions of the same word sit side by side. No wordplay split and no indicators — both halves of the clue define the answer. The full step-by-step breakdown is on this page.

Length of timber that could make a cube (3-2-4)

28A — Length of timber that could make a cube (3-2-4) — TWO-BY-FOUR