First, perhaps, said about noise (7)
I believe the answer is:
ordinal
'first perhaps' is the definition.
(first is a kind of ordinal)
'said about noise' is the wordplay.
'said' becomes 'oral' (I've seen this before).
'about' means one lot of letters goes inside another.
'noise' becomes 'din' (din is a kind of noise).
'oral' enclosing 'din' is 'ORDINAL'.
(Other definitions for ordinal that I've seen before include "It shows your place" , "Possibly first or second" , "Number in a sequence" , "Number such as first or second" , "Numerals such as first and second" .)