Coloured in untidy edges (4)
I believe the answer is:
dyed
'coloured' is the definition.
(dyeing is a kind of colouring)
'in untidy edges' is the wordplay.
'in' indicates the answer is hidden within the clue.
'DYED' is hidden in the letters of 'untidy edges'.
(Other definitions for dyed that I've seen before include "Given a new colour" , "A shade unnatural" , "Imbued with artificual colour" , "(Of fabric) coloured" , "Artificially coloured" .)