At extremities, goes no further (4)
I believe the answer is:
ends
This clue could be a double definition.
'at extremities' is the first definition.
'ends' can be an answer for 'extremities' (end is a kind of extremity). I am unsure of the 'at' bit.
'goes no further' is the second definition.
(I've seen this in another clue)
Can you help me to learn more?
(Other definitions for ends that I've seen before include "Rooms in bothy" , "Halts" , "See 8" , "Completes - purposes" , "Terminates in dens" .)