Offence outspoken seer meant (7)
I believe the answer is:
sincere
'meant' is the definition.
(thesaurus)
'offence outspoken seer' is the wordplay.
'offence' becomes 'sin' (a sin is an offence or transgression).
'outspoken seer' becomes 'cere' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sin'+'cere'='SINCERE'
Can you help me to learn more?
(Other definitions for sincere that I've seen before include "Open and genuine, not deceitful" , "Honest, frank" , "'Genuine, not deceitful (7)'" , "Lacking in deceit" , "Not hypocritical" .)