The colour of one doing wrong? (6)
I believe the answer is:
indigo
'the colour' is the definition.
(indigo is a kind of colour)
'one doing wrong?' is the wordplay.
'one' becomes 'i' (Roman numeral).
'wrong?' indicates an anagram (I've seen 'wronged' mean this).
'doing' anagrammed gives 'ndigo'.
'i'+'ndigo'='INDIGO'
'of' is the link.
(Other definitions for indigo that I've seen before include "Dark blue dye (plant)" , "I of ROYGBIV" , "type of dye" , "Blue/violet dye" , "Deep violet-blue colour" .)