Unusually, perhaps, notice bishop replacing centrepiece of altar (6)
I believe the answer is:
adverb
'unusually perhaps notice' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for adverb that I've seen before include "Verb qualifier" , "It qualifies the predicate in a sentence" , "Word such as 'madly'" , "unwisely, for example" , "Word that qualifies another" .)