Unconventional artist is a brat from across the Channel (6,8)
I believe the answer is:
enfant terrible
'unconventional' is the definition.
(I've seen this before)
'artist is a brat from across the channel' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found in the answer.
'from' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for enfant terrible that I've seen before include "scamp" , "nonconformist" , "wild child - with 30a" , "subject of controversy? - with 10a" , "One behaving controversially" .)