Some sheep somewhere in Derby town (5)
I believe the answer is:
epsom
'derby town' is the definition.
(I've seen this before)
'some sheep somewhere in' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'EPSOM' can be found hidden inside 'sheep somewhere in'.
(Other definitions for epsom that I've seen before include "Home to the Derby and the Oakes" , "Mopes around English Derby venue" , "Derby area" , "Home to the Derby and the Oaks" , "can have horses" .)