Destroy base after ages (5)
I believe the answer is:
erase
'destroy' is the definition.
(I've seen this before)
'base after ages' is the wordplay.
'base' becomes 'e' (Euler's number - base of natural logarithms).
'after' is a charade indicator (letters next to each other).
'ages' becomes 'eras' (I've seen this before).
'e' put after 'eras' is 'ERASE'.
(Other definitions for erase that I've seen before include "Destroy recording on audio or video tape" , "Efface" , "Eliminate" , "Obliterate" , "Remove permanently" .)