Idea from those people keeping gold (6)
I believe the answer is:
theory
'idea' is the definition.
(I know that theory is a type of concept)
'those people keeping gold' is the wordplay.
'those people' becomes 'they' (I've seen this in another clue).
'keeping' indicates putting letters inside.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'they' going around 'or' is 'THEORY'.
'from' acts as a link.
(Other definitions for theory that I've seen before include "The words, as opposed to the practice" , "Opinion or supposition to explain something" , "Justifying hypothesis" , "(Scientific) explanation" , "Supposition or idea" .)