Graded Charlie very behind in speaking (7)
I believe the answer is:
classed
'graded charlie' is the definition.
The answer and definition can be both related to thinking as well as being past participle verbs.
Perhaps there's an association between them I don't understand?
'behind in speaking' is the wordplay.
I cannot really understand how this works, but
'behind' could be 'ass' (both can mean one's back side) and 'ass' is found within the answer.
This explanation may well be incorrect...
'very' acts as a link.
Can you help me to learn more?
(Another definition for classed that I've seen is " put in her place!".)