Alluring beauty finally deserting old Hollywood actress (7)
I believe the answer is:
glamour
'alluring beauty' is the definition.
(I've seen this before)
'finally deserting old hollywood actress' is the wordplay.
'finally' suggests the final letters.
'old hollywood actress' becomes 'lamour' (Dorothy Lamour).
The last letter of 'deserting' is 'g'.
'g'+'lamour'='GLAMOUR'
(Other definitions for glamour that I've seen before include "Appealing and beautiful quality" , "Exciting attractiveness" , "Alluring beauty, very sexy" , "Charm and allure" , "Alluring beauty or charm" .)