Clue: Warn pidgin changes tack in the US (7,3)
Answer: DRAWING PIN
Explanation: Warn pidgin changes tack in the US (7,3)
***(warn pidgin) ***I was a bit bemused by the "in the US" bit of the clue, but Chambers entry for "tack" says "drawing pin (N. Am.)". I've always called tacks drawing pins.