First on display to arrange big noise in RAF (3,5,7)
I believe the answer is:
air chief marshal
'noise in raf' is the definition.
The definition suggests a singular noun which matches the answer.
'first on display to arrange big' is the wordplay.
'first' becomes 'chief'.
'on' means one lot of letters go next to another.
'display' becomes 'air' (I've seen this before).
'to arrange big' becomes 'marshal' (I can't explain this - if you can you should give a lot more credence to this answer).
'chief' after 'air' is 'airchief'.
'airchief'+'marshal'='AIR CHIEF MARSHAL'
Can you help me to learn more?
(Another definition for air chief marshal that I've seen is " Senior officer".)