Bear expert around noon giving tacit assent (10)
I believe the answer is:
sufferance
'tacit assent' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'bear expert around noon' is the wordplay.
'bear' becomes 'suffer' (synonyms).
'expert' becomes 'ace' (ace can informally mean very good).
'around' is an insertion indicator.
'noon' becomes 'n' (abbreviation).
'ace' enclosing 'n' is 'ance'.
'suffer'+'ance'='SUFFERANCE'
'giving' acts as a link.
Can you help me to learn more?
(Other definitions for sufferance that I've seen before include "Reluctant consent" , "No objection" .)