Outline articles, missing her first class (9)
I believe the answer is:
designate
'class' is the definition.
The answer and definition can be both related to thinking as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
'outline articles missing her first' is the wordplay.
'outline' becomes 'design' (I can't explain this - if you can you should believe this answer much more).
'articles' becomes 'a the' ('a' and 'the', indefinite and definite articles).
'missing' indicates named letters should be taken away.
'her first' becomes 'h' (dst letter of 'her').
'athe' with 'h' taken out is 'ate'.
'design'+'ate'='DESIGNATE'
Can you help me to learn more?
(Other definitions for designate that I've seen before include "Appointed but not yet in post" , "Identify" , "Allocate" , "Assign" , "Appoint" .)