Living beyond 100, show evidence of age? (5)
I believe the answer is:
crust
'living' is the definition.
(to earn a crust is to earn a living)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for crust that I've seen before include "Pie topping" , "Hard knowledge" , "Hard exterior" , "Hardened layer; pie top" , "Some bread" .)