A fine headdress means nothing, covered in ice-cream! (7)
I believe the answer is:
coronet
'a fine headdress' is the definition.
'coronet' can be an answer for 'headdress' (coronet is a kind of headdress). I am unsure of the 'a fine' bit.
'nothing covered in ice-cream' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'covered in' indicates putting letters inside.
'ice-cream' becomes 'cornet' (I've seen this before).
'o' going into 'cornet' is 'CORONET'.
'means' is the link.
Can you help me to learn more?
(Other definitions for coronet that I've seen before include "emblem of rank" , "mark of noble rank?" , "Jewelled headgear for peer" , "Sub-lieutenant" , "Jewelled circlet for the head" .)