Star is back, taking over, terribly edgy (7)
I believe the answer is:
nervous
'edgy' is the definition.
(synonyms)
'star is back taking over terribly' is the wordplay.
'star' becomes 'sun' (the Sun is a star).
'is back' shows that the letters should be reversed in order.
'taking' means one lot of letters goes inside another.
'terribly' is an anagram indicator.
'sun' in reverse letter order is 'nus'.
'over' anagrammed gives 'ervo'.
'nus' going around 'ervo' is 'NERVOUS'.
(Other definitions for nervous that I've seen before include "Fearful or apprehensive" , "Highly-strung" , "Jumpy" , "Agitated - excitable" , "'Apprehensive, uneasy (7)'" .)