Vanity formerly present in most of metropolis (7)
I believe the answer is:
conceit
'vanity' is the definition.
(I know that vanity can be written as conceit)
'formerly present in most of metropolis' is the wordplay.
'formerly' becomes 'once' (synonyms).
'present in' indicates putting letters inside.
'most of' means to remove the last letter.
'metropolis' becomes 'city' (a metropolis is a large city).
'city' with its final letter taken away is 'cit'.
'once' going within 'cit' is 'CONCEIT'.
(Other definitions for conceit that I've seen before include "Fanciful notion; excessive pride in oneself" , "Vanity; fanciful notion" , "Fancy; vanity" , "Fanciful notion; self-pride" , "Excessive self-esteem" .)