Terrible noise or disintegration (7)
I believe the answer is:
erosion
'disintegration' is the definition.
(I've seen this before)
'terrible noise or' is the wordplay.
'terrible' is an anagram indicator.
'noise'+'or'='noiseor'
'noiseor' anagrammed gives 'EROSION'.
(Other definitions for erosion that I've seen before include "Gradual decline" , "The wearing away by water or weather" , "Abrasion" , "being eaten away" , "Process of wear" .)