European can't change sanction (5)
I believe the answer is:
enact
'sanction' is the definition.
(I've seen this in another clue)
'european can't change' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'change' indicates an anagram.
'cant' anagrammed gives 'nact'.
'e'+'nact'='ENACT'
(Other definitions for enact that I've seen before include "Bring in" , "Put on stage or statute book" , "Put into practice" , "get into law" , "Decree" .)