A sullen art, playing a comedian (4,6)
I believe the answer is:
stan laurel
'a comedian' is the definition.
(I have seen 'Old comedian' mean 'stan laurel' so perhaps 'comedian' could also mean 'stan laurel')
'a sullen art playing' is the wordplay.
'playing' indicates an anagram.
'a'+'sullen'+'art'='asullenart'
'asullenart' with letters rearranged gives 'STAN LAUREL'.
(Other definitions for stan laurel that I've seen before include "Old comedian" , "US comedian, b. Ulverston (Cumbria) 1890, d. 1965" .)