Truth at the centre of affair, respectfully (4)
I believe the answer is:
fact
'truth' is the definition.
(true facts)
'at the centre of affair respectfully' is the wordplay.
'at' means one lot of letters go next to another.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'centre of' indicates the central letters.
'respectfully' becomes 'c' (I can't justify this - if you can you should believe this answer much more).
The middle letters of 'affair' are 'fa'.
'fa'+'c'='fac'
't' after 'fac' is 'FACT'.
Can you help me to learn more?
(Other definitions for fact that I've seen before include "Actuality" , "True item; reality" , "Not fake news!" , "Indisputable thing" , "Piece of information known to be true" .)