Superman actor on night before (5)
I believe the answer is:
reeve
'superman actor' is the definition.
(I've seen this in another clue)
'on night before' is the wordplay.
'on' becomes 're' (regarding).
'night before' becomes 'eve' (eve can mean the night before something).
're'+'eve'='REEVE'
(Other definitions for reeve that I've seen before include "magistrate of long ago" , "Old official in Bruree, venerated" , "Could 'e ever pass a rope through a hole?" , "High official" , "Old judge" .)