Curler, black, certainly fits round front of wig (8)
I believe the answer is:
bindweed
'curler' is the definition.
(plant which curls around)
'black certainly fits round front of wig' is the wordplay.
'black' becomes 'b' (as in pencil classifications).
'certainly' becomes 'indeed' (both can be used to answer in the affirmative).
'fits round' means one lot of letters goes inside another (some letters go around others).
'front of' indicates taking the first letters.
The initial letter of 'wig' is 'w'.
'indeed' placed around 'w' is 'indweed'.
'b'+'indweed'='BINDWEED'
(Other definitions for bindweed that I've seen before include "Be winded (anag.)" , "Twining invasive plant" , "Convolvulus" , "Strangler" , "Gardener's bane - widen bed (anag)" .)