Heavy rock? (5)
I believe the answer is:
stone
This clue could be a double definition.
'heavy' is the first definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I can't see?
'rock?' is the second definition.
(I know that rock can be written as stone)
Can you help me to learn more?
(Other definitions for stone that I've seen before include "14 lb" , "Hard lump of mineral matter" , "Gem; Staffs. town" , "diamond, say" , "Rock; gem" .)