Central bar alongside square in bustling metro (9)
I believe the answer is:
innermost
'square in bustling metro' is the definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?
'central bar alongside' is the wordplay.
'central' becomes 'inner' (similar in meaning).
'bar alongside' becomes 'most' (I can't explain this - if you can you should give a lot more credence to this answer).
'inner'+'most'='INNERMOST'
Can you help me to learn more?
(Other definitions for innermost that I've seen before include "Sort of secrets" , "Who may have gone deepest" , "Closest to the centre" , "Furthest in" , "Private" .)