warming pan

noun2

1. •
   A covered metal pan attached to a long handle, holding live coals and used to warm a bed.

   • Good Bardolfe / Put thy nose betweene the sheetes, and do the office of a warming pan. — 1599
2. •
   (figurative, old-fashioned) A person put into a situation to hold it until another person can take over.

   • We used to call him in my parliamentary time W. P. Adams, in consequence of his being Warming Pan for a young fellow who was in his minority. — 1846