Good profit by following a source of rare stone (6)
I believe the answer is:
garnet
'stone' is the definition.
(thesaurus)
'good profit by following a source of rare' is the wordplay.
'good' becomes 'g' (abbreviation).
'profit by' becomes 'net' (netting is a kind of profiting. I am not sure about the 'by' bit.**).
'following' is a charade indicator (letters next to each other).
'source of' indicates taking the first letters.
The first letter of 'rare' is 'r'.
'a'+'r'='ar'
'net' put after 'ar' is 'arnet'.
'g'+'arnet'='GARNET'
Can you help me to learn more?
(Other definitions for garnet that I've seen before include "Precious stone, usually red" , "January birthstone" , "Deep red gem stone" , "Hard glassy mineral used as a gemstone" , "Semi-precious stone of argent type" .)