Offence caused by very French attempt at seduction (8)
I believe the answer is:
trespass
'offence' is the definition.
(I've seen this before)
'very french attempt at seduction' is the wordplay.
'very french' becomes 'tres' ('very' in French).
'attempt at seduction' becomes 'pass' (I can't explain this - if you can you should believe this answer much more).
'tres'+'pass'='TRESPASS'
'caused by' is the link.
Can you help me to learn more?
(Other definitions for trespass that I've seen before include "Entry without permission" , "Illegal entry" , "Go where one shouldn't" , "Transgress" , "Go out of bounds" .)