Early versions of coinage, amongst the smallest ones (9)
I believe the answer is:
rudiments
'early versions' is the definition.
The answer and definition can be both related to thinking as well as being plural nouns.
Maybe you can see an association between them that I can't see?
'coinage amongst the smallest ones' is the wordplay.
'coinage' becomes 'dime' (dime is a kind of coinage).
'amongst' indicates putting letters inside (I've seen this in other clues).
'the smallest ones' becomes 'runts' (I can't justify this - if you can you should believe this answer much more).
'dime' put within 'runts' is 'RUDIMENTS'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for rudiments that I've seen before include "basic principles" , "Basics of any subject" .)