“What "R" might stand for on an envelope”

Grammy-winning singer who's had both a "Farewell Tour" and a "Here We Go Again Tour"

Carry out orders

Some images carved in Egyptian tombs

Class that might be all play and no work?

"Seriously, dude …"

One robed in a kittel, maybe

Part of an evacuation plan

Former carrier over Mauna Kea

References as references