Possibly buries gems (6)
I believe the answer is:
rubies
'gems' is the definition.
(I know this)
'possibly buries' is the wordplay.
'possibly' is an anagram indicator.
'buries' anagrammed gives 'RUBIES'.
(Other definitions for rubies that I've seen before include "The Stones in the red" , "Deep red gems" , "Deep red jewels" , "Red gemstones" .)