Keep going to the end (4)
I believe the answer is:
last
I believe this is a double definition.
'keep going' is the first definition.
(I've seen this before)
'the end' is the second definition.
(I've seen this before)
'to' acts as a link.
(Other definitions for last that I've seen before include "model for a leprechaun" , "Hold out" , "part of Oxford's restoration with this?" , "It helps cobbler" , "Latest" .)