Work to protect old city with millions in trouble (7)
I believe the answer is:
turmoil
'trouble' is the definition.
(thesaurus)
'work to protect old city with millions' is the wordplay.
'work' becomes 'toil' (toil is a kind of work).
'to protect' indicates putting letters inside (inserted letters are protected or taken in).
'old city' becomes 'ur' (ancient Sumerian city state).
'with' is a charade indicator (letters next to each other).
'millions' becomes 'm' (abbreviation).
'ur'+'m'='urm'
'toil' placed around 'urm' is 'TURMOIL'.
'in' acts as a link.
(Other definitions for turmoil that I've seen before include "Uproar" , "racket" , "Sturm und Drang" , "Tumult, upheaval" , "Violent commotion" .)