Poet has day off to take up something Sicilian (4)
I believe the answer is:
etna
'something sicilian' is the definition.
(Sicilian volcano)
I can't explain the rest of the clue.
(Other definitions for etna that I've seen before include "Constant smoker" , "Volcanic mount in Sicily" , "Italian smoker" , "source of fumes?" , "smoker in Sicily" .)