Age certain to produce obliteration (7)
I believe the answer is:
erasure
'obliteration' is the definition.
(I've seen this before)
'age certain' is the wordplay.
'age' becomes 'era' (both can mean a long time).
'certain' becomes 'sure' (synonyms).
'era'+'sure'='ERASURE'
'to produce' is the link.
(Other definitions for erasure that I've seen before include "Effect of surface damage" , "Rubbing out - English synthpop duo" , "Obliteration of data" , "group from the 80s" , "clearing of tape" .)