Answer: beatsadeadhorse

AnswerCrossword Clue
BEATSADEADHORSE

Revives an exhausted topic

BEATSADEADHORSE

Wastes effort, in a way

BEATSADEADHORSE

Argues an issue that's already settled

BEATSADEADHORSE
Goes on and on, in a way
BEATSADEADHORSE
Rehashes again and again