Genuine guilt before snorting cocaine (7)
I believe the answer is:
sincere
'genuine' is the definition.
(synonyms)
'guilt before snorting cocaine' is the wordplay.
I cannot really see how this works, but
'before' could be 'ere' (usually literary) and 'ere' is found in the answer.
'cocaine' could be 'c' (drugs abbreviation) and 'c' is located in the answer.
The remaining letters 'sin' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sincere that I've seen before include "'Genuine, not deceitful (7)'" , "devout" , "Honest, heartfelt" , "Unaffected" , "Genuine; deceit-free" .)