Keep, somehow, to sandwich course (5)
I believe the answer is:
epsom
'course' is the definition.
(a race course)
'keep somehow to sandwich' is the wordplay.
'to sandwich' indicates a hidden word (I've seen 'sandwiches' mean this (the answer is sandwiched in by the clue)).
'EPSOM' is hidden in the letters of 'keep somehow'.
(Other definitions for epsom that I've seen before include "can have horses" , "Derby course" , "Poems about the race-course" , "Home to the Derby and the Oakes" , "English town, of course?" .)