In a precarious position in hot foggy French city (2,4,3)
I believe the answer is:
on thin ice
'foggy french city' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'in a precarious position in hot' is the wordplay.
'in' is an insertion indicator.
'a' becomes 'one'.
'precarious position' becomes 'thic' (I am not sure about this - if you are sure you should believe this answer much more).
'in' indicates putting letters inside.
'hot' becomes 'in' (both can mean fashionable).
'one' enclosing 'thic' is 'onthice'.
'onthice' going around 'in' is 'ON THIN ICE'.
Can you help me to learn more?
(Other definitions for on thin ice that I've seen before include "In a difficult position" , "In a risky situation" , "In a precarious situation" , "like a daredevil skater?" , "At risk" .)