Reportedly off colour, but that's what I meant (3)
I believe the answer is:
sic
'reportedly' is the definition.
Both the answer and definition are adverbs. Maybe you can see an association between them that I don't see?
'colour but that's what i meant' is the wordplay.
I cannot really see how this works, but
'i' is within the answer.
'that's' could be 'sc' (short for Latin scilicet- 'it follows' or 'that is) and 'sc' is present in the remaining letters.
No letters remain.
This explanation may well be incorrect...
'off' is the link.
Can you help me to learn more?
(Other definitions for sic that I've seen before include "Written exactly thus" , "poorly spelt if requiring this" , "Like" , "'Thus, in printing (3)'" , "Printing term to denote accuracy though it appears otherwise" .)