A seasoned couple (6)
I believe the answer is:
salted
'a seasoned' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for salted that I've seen before include "Lasted, being preserved" , "cured" , "Seasoned, given piquancy; (of meat) preserved" , "Like some nuts" .)