Course creep's omitted? Not altogether (5)
I believe the answer is:
epsom
'course' is the definition.
(I've seen this before)
'creep's omitted? not altogether' is the wordplay.
'not altogether' indicates a hidden word.
'EPSOM' is hidden within 'creeps omitted'.
(Other definitions for epsom that I've seen before include "Derby course" , "Town with racecourse" , "Poems about the race-course" , "Surrey race course" , "Classic venue" .)