Weak or worn out through age (8)
I believe the answer is:
decrepit
This clue is a double definition.
'weak' is the first definition.
(I know that weak can be written as decrepit)
'worn out through age' is the second definition.
(I've seen this before)
(Other definitions for decrepit that I've seen before include "Cited rep for being old and dilapidated" , "Old and feeble" , "Old and infirm" , "past its best" , "Feeble - dilapidated" .)