Well, Silver Cervy, I read your post too quickly and thought you said the clunk happened on acceleration also.
So, I'll go with a brake problem, either a lose pad, a lose caliper.
Then again, it could be a lose rear axle nut.
As for YOU @
Ultramaroon .......
...... the OP stated that the clunk was "definitely coming from the right rear corner of the car". Are their control or toe arm bushings in the rear of the car .....??
Keep us posted.
humfrz