Arduous piece for two performers (3)
I believe the answer is:
duo
'two performers' is the definition.
(I've seen this in another clue)
'arduous piece' is the wordplay.
'piece' says the answer is hidden in the clue.
'DUO' is hidden within 'arduous'.
'for' is the link.
(Other definitions for duo that I've seen before include "They might play" , "entertainers such as Eric and Ernie" , "Pair of people/things" , "Double act" , "A team of two" .)