Capital never safeguarded by locks, ultimately lost (5)
I believe the answer is:
hanoi
'capital' is the definition.
(capital of Vietnam)
'never safeguarded by locks ultimately lost' is the wordplay.
I cannot really understand how this works, but
'never' could be 'no' (I've seen this in other clues) and 'no' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hanoi that I've seen before include "Asian city" , "Vietnamese city" , "Asian capital on the Red River" , "capital out East" , "Vietnamese capital" .)