Performing in short stockings later this evening (7)
I believe the answer is:
tonight
'later this evening' is the definition.
(I've seen this before)
'performing in short stockings' is the wordplay.
'performing' becomes 'on' (as in being on stage).
'in' means one lot of letters goes inside another.
'short' means to remove the last letter.
'stockings' becomes 'tights' (tights can mean stockings).
'tights' with its last letter removed is 'tight'.
'on' placed inside 'tight' is 'TONIGHT'.
(Other definitions for tonight that I've seen before include ""Not ____, Josephine!"" , "Dark time ahead" , "Later this evening" , "later in the day" , "Hotting up for after sundown" .)