Some historians were duly acknowledged (8)
I believe the answer is:
answered
'acknowledged' is the definition.
The answer and definition can be both related to thinking as well as being past participle verbs.
Maybe there's a link between them I don't understand?
'some historians were duly' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'ANSWERED' is hidden in the letters of 'historians were duly'.
Can you help me to learn more?
(Other definitions for answered that I've seen before include "Rejoined" , "Replied or responded" , "Sawn reed (anag.)" , "was sufficient" , "Fulfilled" .)