Sadie, upset when separated (5)
I believe the answer is:
aside
'separated' is the definition.
Both the definition and answer are adverbs. Maybe you can see an association between them that I don't see?
'sadie upset' is the wordplay.
'upset' indicates anagramming the letters.
'sadie' anagrammed gives 'ASIDE'.
'when' is the link.
Can you help me to learn more?
(Other definitions for aside that I've seen before include "Line spoken to theatre audience" , "Remark by an actor, directly to audience say" , "Separately" , "Words spoken apart in an undertone" , "Line spoken to the audience of a play" .)