Description of artist with sex appeal supporting Calais, perhaps (8)
I believe the answer is:
portrait
'description' is the definition.
(I know that portrait is a type of characterisation)
'artist with sex appeal supporting calais perhaps' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'with' means one lot of letters go next to another.
'sex appeal' becomes 'it'.
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'calais perhaps' becomes 'port' (Calais is a port in France).
'ra'+'it' is 'rait'.
'rait' put after 'port' is 'PORTRAIT'.
'of' acts as a link.
(Other definitions for portrait that I've seen before include "Person's picture" , "Painting of a real person" , "Oil perhaps" , "Type of painting" , "Painted likeness of a person" .)