Due to get picked up along with au pair (3)
I believe the answer is:
duo
'pair' is the definition.
(synonyms)
I can't explain the rest of the clue.
(Other definitions for duo that I've seen before include "Two-person act" , "Musical work for two" , "Pair of people/things" , "rejected Arab's lute" , "entertainers such as Eric and Ernie" .)