A crony ruined drawing implement (6)
I believe the answer is:
crayon
'drawing implement' is the definition.
(crayons are used for drawing)
'a crony ruined' is the wordplay.
'ruined' indicates anagramming the letters.
'a'+'crony'='acrony'
'acrony' with letters rearranged gives 'CRAYON'.
(Other definitions for crayon that I've seen before include "Drawing pen" , "Waxy pencil" , "alternative to charcoal" , "One colours with this" , "(Draw with) a coloured stick" .)