Note the number, woman! (5)
I believe the answer is:
ethel
'woman' is the definition.
(I've seen this before)
'note the number' is the wordplay.
'note' becomes 'e' (musical note).
'number' becomes 'l' (L is an example).
'e'+'the'+'l'='ETHEL'
(Other definitions for ethel that I've seen before include "woman" , "Female name" , "Dame - Smyth, Eng. composer, suffragette" , "girl" , "Dame --- Smyth; William Brown's sister" .)