Old temptress called up to lure in lascivious leader (7)
I believe the answer is:
delilah
'old temptress' is the definition.
(Biblical figure)
'called up to lure in lascivious leader' is the wordplay.
'called' becomes 'hailed' (hailing is a kind of calling).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'to lure in' means one lot of letters goes inside another.
'leader' indicates taking the first letters.
The initial letter of 'lascivious' is 'l'.
'hailed' written backwards gives 'deliah'.
'deliah' placed around 'l' is 'DELILAH'.
(Other definitions for delilah that I've seen before include "See 8 across" , "She cut Samson's hair" , "Samson's false girl-friend" , "Samson's destroyer" , "Biblical temptress" .)