One stops interfering, becoming vociferous (5)
I believe the answer is:
noisy
'vociferous' is the definition.
(similar in meaning)
'one stops interfering' is the wordplay.
'one' becomes 'i' (roman numeral).
'stops' is an insertion indicator.
'interfering' becomes 'nosy'.
'i' going into 'nosy' is 'NOISY'.
'becoming' acts as a link.
(Other definitions for noisy that I've seen before include "ear-piercing maybe!" , "Rowdy" , "Loud, rackety" , "Disturbingly loud" , "Full of disturbing sounds" .)