Made too much of duty to conceal mistake in dictionary (9)
I believe the answer is:
overrated
'made too much' is the definition.
The answer and definition can be both related to thinking as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?
'duty to conceal mistake in dictionary' is the wordplay.
'duty' becomes 'vat' (I can't explain this - if you can you should give a lot more credence to this answer).
'to conceal' indicates putting letters inside.
'mistake' becomes 'err' (to err is to make a mistake or blunder).
'in' indicates putting letters inside.
'dictionary' becomes 'OED' (Oxford English Dictionary).
'vat' enclosing 'err' is 'verrat'.
'verrat' put into 'oed' is 'OVERRATED'.
'of' is the link.
Can you help me to learn more?
(Other definitions for overrated that I've seen before include "Thought too highly of" , "Valued too highly, not as good as believed to be" , "Given excessive merit" , "Too highly esteemed" .)