Those people holding gold as a speculation (6)
I believe the answer is:
theory
'a speculation' is the definition.
(thesaurus)
'those people holding gold' is the wordplay.
'those people' becomes 'they' (I've seen this before).
'holding' is an insertion indicator.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'they' going around 'or' is 'THEORY'.
'as' acts as a link.
(Other definitions for theory that I've seen before include "General principle which explains some aspect of the world" , "Suggested explanation" , "Explanation or system of anything" , "(Scientific) explanation" , "Supposition, set of ideas" .)