One inhibited by noisy plaintiff (8)
I believe the answer is:
claimant
'plaintiff' is the definition.
(thesaurus)
'one inhibited by noisy' is the wordplay.
'one' becomes 'i' (Roman numeral).
'inhibited by' is an insertion indicator (I've seen this in other clues).
'noisy' becomes 'clamant' ('clamant' can be similar in meaning to 'noisy').
'i' placed within 'clamant' is 'CLAIMANT'.
(Other definitions for claimant that I've seen before include "Litigant" , "Person seeking payout" , "Pretender" , "Petitioner" , "One making an assertion" .)