Willowy Kate Moss illustration partly printed upside-down (7)
I believe the answer is:
lissome
'willowy' is the definition.
(I've seen this in another clue)
'kate moss illustration partly printed upside-down' is the wordplay.
'partly' indicates the answer is hidden within the clue (part of the clue is used).
'printed upside-down' says the letters should be written backwards.
'emossil' is hidden within 'kate moss illustration'.
'emossil' backwards is 'LISSOME'.
(Other definitions for lissome that I've seen before include "flexible" , "Willowy" , "Moving supply" , "Thin - supple - graceful" , "Oil mess (anag)" .)