Grasped stout and sheltered (8)
I believe the answer is:
fathomed
'grasped' is the definition.
The answer and definition can be both related to thinking as well as being past participle verbs.
Perhaps you can see a link between them that I don't see?
'stout and sheltered' is the wordplay.
'stout' becomes 'fat' (similar in meaning).
'and' means one lot of letters go next to another.
'sheltered' becomes 'homed' (I can't justify this - if you can you should give a lot more credence to this answer).
'fat'+'homed'='FATHOMED'
Can you help me to learn more?
(Other definitions for fathomed that I've seen before include "Got" , "Deeply understood" , "Sounded" .)