Disclose how age impaired a futile mission (4-5,5)
I believe the answer is:
wild-goose chase
'a futile mission' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'disclose how age impaired' is the wordplay.
'impaired' indicates an anagram.
'disclose'+'how'+'age'='disclosehowage'
'disclosehowage' anagrammed gives 'WILD-GOOSE CHASE'.
Can you help me to learn more?
(Other definitions for wild-goose chase that I've seen before include "Hopeless quest" , "Futile quest" , "A foolish pursuit" .)