— MINED (5), OR (2), NEW (3), DATA (4) — yes, that fits perfectly. “Mined or new data” = useful material (mined) or knowledge (new data). That works in cryptic clue style, possibly with “or” as the link.
Write it in your grid as:
In the context of a crossword, "useful material or knowledge" is a literal definition of the idiom. In modern usage, if someone says a particular experience or piece of information is "grist to the mill," they mean it can be used to their advantage, often as inspiration for creative work or as evidence in an argument. Breakdown of the (5, 2, 3, 4) Structure: Why Crossword Setters Love It useful material or knowledge crossword clue 5 2 3 4
Useful material or knowledge; something that can be used to one's advantage. Pattern (5, 2, 3, 4): GRIST (5) TO (2) THE (3) MILL (4) How can I help you finish the rest of the puzzle? If you have a different letter count , let me know. — MINED (5), OR (2), NEW (3), DATA