Make Someone Angry by Waving a __ at a Bull

This page is the CodyCross answer for the clue below from Train Travel, Group 718, Puzzle 4 (Rapid Transit).

Question is: Make Someone Angry by Waving a __ at a Bull

and the answer is: REDRAG

Word Meaning:

RED RAG — (figurative) Something that will enrage another particular person.

Definitions from Wiktionary.