Stop advancing years causing harm (6)
I believe the answer is:
damage
'harm' is the definition.
(I know that harm can be written as damage)
'stop advancing years' is the wordplay.
'stop' becomes 'dam' (I've seen this in other clues).
'advancing years' becomes 'age' (a person's age).
'dam'+'age'='DAMAGE'
'causing' acts as a link.
(Other definitions for damage that I've seen before include "To vandalise" , "Harm, loss" , "Impair and lower value" , "Mar" , "Impairment, injury" .)