Creed is in trouble about European court order (6,4)
I believe the answer is:
decree nisi
'court order' is the definition.
(I've seen this before)
'creed is in trouble about european' is the wordplay.
'trouble' is an anagram indicator.
'about' means one lot of letters goes inside another.
'european' becomes 'e' (abbreviation e.g. EU).
'creed'+'is'+'in'='creedisin'
'creedisin' anagrammed gives 'dcreenisi'.
'dcreenisi' placed around 'e' is 'DECREE NISI'.
(Other definitions for decree nisi that I've seen before include "Judicial order" , "Provisional divorce order" , "Separation agreement" , "court order" , "Provisional divorce document" .)