You three, right away! (4)
I believe the answer is:
thee
'you' is the definition.
(I've seen this before)
'three right away' is the wordplay.
'right' becomes 'r' (common abbreviation).
'away' indicates named letters should be taken away.
'three' with 'r' removed is 'THEE'.
(Other definitions for thee that I've seen before include "Quaker 'you'" , "You in the olden days" , "you many years ago" , "Old objective second person singular" , "Poetically you" .)