Leave armchair and put eggheads back in their place (3,2)
I believe the answer is:
get up
'leave' is the definition.
The definition and answer can be both related to thinking as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for get up that I've seen before include "Clobber" , "Clothes" , "gear" , "Study" , "Suitable term for climbing" .)