One flogging a dead horse, possibly, Rex admits it's wrong (11)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

Anagram [wrong] of REX ADMITS IT’S. A rather fine cryptic definition. When Roy Rogers’ horse Trigger died in 1965, Rogers had the hide professionally stretched over a foam likeness of the horse and mounted in his signature rearing pose. For many years Trigger was on display at a Roy Rogers museum, but following closure he relocated to a TV station headquarters in Nashville, Tennessee where he remains a popular tourist attraction.