Short, high sound from the odd bullet kept border free (5)
I believe the answer is:
bleep
'short high sound' is the definition.
'bleep' can be an answer for 'sound' (I have seen 'Electronic sound ' mean 'bleep' so perhaps 'sound' could also mean 'bleep'). I'm not sure about the 'short high' bit.
'odd bullet kept border free' is the wordplay.
'odd' means one should take alternating letters.
'kept border free' becomes 'ep' (I can't justify this - if you can you should give a lot more credence to this answer).
The alternate letters of 'bullet' are 'ble'.
'ble'+'ep'='BLEEP'
'from the' is the link.
Can you help me to learn more?
(Other definitions for bleep that I've seen before include "Swearing substitute" , "covers swearing" , "Electronic alarm sound" , "Noise of alarm" , "Short high tone as a signal or warning" .)