Reddish gem (6)
I believe the answer is:
garnet
'reddish gem' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for garnet that I've seen before include "Deep red gemstone" , "Hard glassy mineral used as a gemstone" , "Semi-precious stone of deep transparent red" , "Precious stone, usually red" , "Semi-precious stone of argent type" .)