Some unsavoury task upset woodland deity (5)
I believe the answer is:
satyr
'woodland deity' is the definition.
(I've seen this before)
'some unsavoury task upset' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'upset' says the letters should be written backwards.
'rytas' can be found hidden inside 'unsavoury task'.
'rytas' in reverse letter order is 'SATYR'.
(Other definitions for satyr that I've seen before include "lecher" , "Goatlike deity of Greek myth" , "Woodland deity, attendant on Bacchus" , "Woodland god - sexual predator" , "Oversexed chap" .)