Gathers dust (4)
'gathers' is the definition.
The definition and answer can be both related to thinking as well as being verbs in their -s form.
Maybe there's a link between them I don't understand?
'dust?' is the wordplay.
I cannot quite understand how this works, but
'dust?' could be 'sweep' (I've seen this before) and 'sweep' is present in the answer.
The remaining letters 'sup' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
'gathers dust' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sits that I've seen before include "Is in session" , "Takes a chair" , "Perches" , "Poses for portrait" , "Takes a seat for the painter" .)