Just a ban, or else reforms (10)
I believe the answer is:
reasonable
'just' is the definition.
('reasonable' is associated in meaning with 'just')
'a ban or else reforms' is the wordplay.
'reforms' indicates an anagram.
'a'+'ban'+'or'+'else'='abanorelse'
'abanorelse' is an anagram of 'REASONABLE'.
(Other definitions for reasonable that I've seen before include "Sound" , "Not excessive or extreme" , "Fair, rational" , "description of rationality" , "Fair - inexpensive" .)