Barrier protecting my city (8)
I believe the answer is:
florence
'city' is the definition.
(Florence is an example)
'barrier protecting my' is the wordplay.
'barrier' becomes 'fence' (fence is a kind of barrier).
'protecting' is an insertion indicator (inserted letters are held or protected).
'my' becomes 'lor' (exclamation of surprise).
'fence' enclosing 'lor' is 'FLORENCE'.
(Other definitions for florence that I've seen before include "Firenze" , "Name of girl ? city" , "foreign city" , "Angel of the reclining (anag) -- nurse" , "Brunelleschi's birthplace" .)