Colouring by hand drawn by the old you (3-3)
I believe the answer is:
tie-dye
'colouring' is the definition.
(I know that tie dye is a type of dyeing)
'hand drawn by the old you' is the wordplay.
I cannot quite see how this works, but
'drawn' could be 'tied' ('tie' can be a synonym of 'draw') and 'tied' is present in the answer.
'you' could be 'ye' (historical version of 'you') and 'ye' is found within the answer.
No letters remain.
This explanation may well be incorrect...
'by' is the link.
Can you help me to learn more?
(Other definitions for tie-dye that I've seen before include "Method of colouring garment in which it is knotted" , "Colour (cloth) in a particular way" , "hippies do this" , "Clothing style" , "method of patterning textiles" .)