Like Scotch whisky (4)
I believe the answer is:
aged
'like scotch whisky' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aged that I've seen before include "not a modern copy" , "Elderly" , "Very old, person or wine" , "Matured like wine in wood" , "well over the hill" .)