Checks out female beasts of burden? (8)
I believe the answer is:
assesses
'checks out female' is the definition.
The answer and definition can be both related to thinking as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?
'beasts of burden?' is the wordplay.
'beasts' becomes 'asses' (I have seen 'Beasts of burden' mean 'asses' so perhaps 'beasts' could also mean 'asses').
'of burden?' becomes 'ses' (I can't justify this - if you can you should give a lot more credence to this answer).
'asses'+'ses'='ASSESSES'
Can you help me to learn more?
(Other definitions for assesses that I've seen before include "Carries out tests" , "Judges the worth of" .)