Behave theatrically, aloof right away (5)
I believe the answer is:
emote
'behave theatrically' is the definition.
(to emote is to display emotion)
'aloof right away' is the wordplay.
'aloof' becomes 'remote' (I've seen this in another clue).
'right' becomes 'r' (common abbreviation).
'away' indicates named letters should be taken away.
'remote' with 'r' taken out is 'EMOTE'.
(Other definitions for emote that I've seen before include "Show extreme feelings" , "Cry freely" , "give excessive show of feelings" , "Openly show feelings" , "Show feelings excessively" .)