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' indicates named letters should be taken away.
'second' becomes 's' (common abbreviation).
'retrospective' says the letters should be written backwards.
'degas' with 's' taken out 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" .)