Old impressionist releases second retrospective (4)
I believe the answer is:
aged
'old' is the definition.
(similar in meaning)
'impressionist releases second retrospective' is the wordplay.
'impressionist' becomes 'degas' (I've seen this before).
'releases' is a deletion indicator.
'second' becomes 's' (common abbreviation).
'retrospective' shows that the letters should be reversed in order.
'degas' with 's' removed is 'dega'.
'dega' in reverse letter order is 'AGED'.
(Other definitions for aged that I've seen before include "Getting on" , "not a modern copy" , "Time-worn" , "Like Uncle Arly" , "Elderly" .)