Sewing tools can be a pain (4,3,7)
I believe the answer is:
pins and needles
'pain' is the definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'sewing tools can be a' is the wordplay.
I cannot quite see how this works, but
'be' could be 'need' (needing is a kind of being) and 'need' is present in the answer.
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for pins and needles that I've seen before include "Numbness" , "Cushions and cases provided for such" , "that may lead to stitches?" , "these are sharp" , "Prickly attack" .)