Christmas visitor, Florence, on vacation in US city (5,2)
I believe the answer is:
santa fe
'us city' is the definition.
(I've seen this before)
'christmas visitor florence on vacation' is the wordplay.
'christmas visitor' becomes 'santa' (I've seen this before).
'on vacation' means to remove the middle letters (after the inside letters have vacated the word).
'florence' with its centre taken out is 'fe'.
'santa'+'fe'='SANTA FE'
'in' acts as a link.
(Other definitions for santa fe that I've seen before include "US state capital" , "Capital of New Mexico state" , "US city" , "Capital city of New Mexico" .)