Overhauled Porsche not right for ages (6)
I believe the answer is:
epochs
'for ages' is the definition.
(I've seen this before)
'overhauled porsche not right' is the wordplay.
'overhauled' is an anagram indicator.
'not' is a deletion indicator.
'right' becomes 'r' (common abbreviation).
'porsche' with 'r' taken out is 'posche'.
'posche' anagrammed gives 'EPOCHS'.
(Other definitions for epochs that I've seen before include "Periods of historical time" , "'Periods, eras (6)'" , "Vast periods of time" , "Eras, subdivisions of time" , "Distinctive periods in history" .)