Onion place - possibly descriptive of France at some time (10)
I believe the answer is:
napoleonic
'descriptive of france at some time' is the definition.
'onion place possibly' is the wordplay.
'possibly' is an anagram indicator.
'onion'+'place'='onionplace'
'onionplace' is an anagram of 'NAPOLEONIC'.
(Other definitions for napoleonic that I've seen before include "Relating to a particular French emperor" , "Relating to Bonaparte" , "The -- Code is a legal system in France" , "Old French" .)