Clue: 90% discount on opening of neighbourhood business — approach succeeded — they make some noise (5,5)
Answer: VOCAL CORDS
Explanation: Definition: they make some noise
A charade of VOCAL, which is LOCAL ('neighbourhood') with the initial L replaced by V (Roman numerals, 50 replaced by 5, '90% discount on opening') plus CO (company, 'business') plus RD (road, 'approach') plus S ('succeeded').