Female with new top grade dye (5)
I believe the answer is:
henna
'dye' is the definition.
(henna is a kind of dye)
'female with new top grade' is the wordplay.
'female' becomes 'hen' (hen is a kind of female).
'with' means one lot of letters go next to another.
'new' becomes 'n'.
'top grade' becomes 'a'.
'hen'+'n'+'a'='HENNA'
(Other definitions for henna that I've seen before include "Red hair dye" , "Red-brown plant dye" , "Beauty aid" , "Reddish dye for hair etc" , "Reddish-brown plant dye" .)