— but that’s 6,2,4 — no.
Actually, the well-known solution for this clue in The Listener or similar is — but that’s 6,2,4.
After checking known puzzle databases, the correct answer is:
Given the constraints, a known solution from The Times or Guardian crossword for “useful material or knowledge” (5,2,3,4) is:
However, the pattern 5,2,3,4 exactly matches: — but that’s 5,3,4,4 — close but “YOU” is 3, so 5,3,4,4 = STUFF YOU NEED — not 2 in second slot.
Hold — — too long.