Man on the street grabs Miss India, disregarding metro’s chief police officer (12)
I believe the answer is:
commissioner
'police officer' is the definition.
'man on the street grabs miss india disregarding' is the wordplay.
'man on the street' becomes 'commoner'.
'grabs' means one lot of letters goes inside another.
'miss india disregarding' becomes 'issi' (I can't explain this - if you can you should believe this answer much more).
'commoner' going around 'issi' is 'COMMISSIONER'.
'metro's chief' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
(Other definitions for commissioner that I've seen before include "Head of police organisation" , "Senior policeman" , "Representative or head of a high authority" .)