Aware of congregations banishing ogre, vaguely (9)
I believe the answer is:
cognisant
'aware of' is the definition.
(I've seen this before)
'congregations banishing ogre vaguely' is the wordplay.
'banishing' is a deletion indicator.
'vaguely' is an anagram indicator.
'congregations' with 'ogre' taken out is 'cngations'.
'cngations' anagrammed gives 'COGNISANT'.
(Other definitions for cognisant that I've seen before include "Aware of" , "Knowledgeable" , "Having knowledge or understanding" .)