Chap getting old, but coping (8)
I believe the answer is:
managing
'coping' is the definition.
('manage' can be a synonym of 'cope')
'chap getting old' is the wordplay.
'chap' becomes 'man' (I've seen this before**).
'getting old' becomes 'aging' (I've seen this before).
'man'+'aging'='MANAGING'
'but' is the link.
(Other definitions for managing that I've seen before include "Running; coping" , "Handling" .)