One trades prototypes (6)
I believe the answer is:
ideals
'prototypes' is the definition.
The definition and answer can be both related to thinking as well as being plural nouns.
Maybe they are linked in a way I don't understand?
'one trades' is the wordplay.
'one' becomes 'i' (roman numeral).
'trades' becomes 'deals' ('deal' can be a synonym of 'trade').
'i'+'deals'='IDEALS'
Can you help me to learn more?
(Other definitions for ideals that I've seen before include "Ethics" , "Models of excellance" , "Principles to live up to" , "Standards to be aimed at" , "100%? > 10 out out of 10? > With capital, more would want these" .)