Maybe Emil's so supple (7)
I believe the answer is:
lissome
'supple' is the definition.
(I know that supple can be written as lissome)
'maybe emil's so' is the wordplay.
'maybe' indicates anagramming the letters.
'emils'+'so'='emilsso'
'emilsso' with letters rearranged gives 'LISSOME'.
(Other definitions for lissome that I've seen before include "Willowy" , "Thin - supple - graceful" , "Slim, supple, graceful" , "flexible" , "So smile, being agile and lithe" .)