The first gold being held by speculator (8)
I believe the answer is:
theorist
'speculator' is the definition.
(I've seen this before)
'the first gold being held' is the wordplay.
'first' becomes 'ist'.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'being held' is an insertion indicator.
'the'+'ist'='theist'
'theist' enclosing 'or' is 'THEORIST'.
'by' is the link.
(Other definitions for theorist that I've seen before include "Speculator" , "Expert in established hypotheses" , "An expert in abstract principles" , "Creator of hypothesis" , "Abstract reasoner" .)