Heavy dark cloud (6)
I believe the answer is:
nimbus
(Other definitions for nimbus that I've seen before include "A rain-cloud or a halo" , "A kind of rain-cloud, or 15 Across" , "Large grey rain cloud" , "round one's head?" , "Storm cloud" .)
I believe the answer is:
nimbus
(Other definitions for nimbus that I've seen before include "A rain-cloud or a halo" , "A kind of rain-cloud, or 15 Across" , "Large grey rain cloud" , "round one's head?" , "Storm cloud" .)