Work to tour old city facing mass commotion (7)
I believe the answer is:
turmoil
'commotion' is the definition.
('turmoil' can be a synonym of 'commotion')
'work to tour old city facing mass' is the wordplay.
'work' becomes 'toil' (toiling is a kind of working**).
'to tour' is an insertion indicator (to tour can mean to go around).
'old city' becomes 'ur' (ancient city state).
'facing' is a charade indicator (letters next to each other).
'mass' becomes 'm' (symbol used in Physics e.g. f=ma).
'ur'+'m'='urm'
'toil' enclosing 'urm' is 'TURMOIL'.
(Other definitions for turmoil that I've seen before include "Unrest - upheaval" , "State of great commotion or disturbance" , "Sturm und Drang" , "Wild disorder" , "Disquiet" .)