Long to have smart clothing? Sewing is required (9)
I believe the answer is:
stitching
'sewing is required' is the definition.
I can't judge whether this defines the answer.
'long to have smart clothing?' is the wordplay.
'long' becomes 'itch' (to long or itch for something is to desire it).
'to have smart' becomes 'sting' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'clothing?' indicates putting letters inside (some letters cover up or clothe others).
'itch' inserted into 'sting' is 'STITCHING'.
Can you help me to learn more?
(Other definitions for stitching that I've seen before include "Fasten by sewing" , "achieving closure of wound" , "Sutures" , "Using needle and thread" , "Perhaps is repairing" .)