Kind of milkman (3)
I believe the answer is:
ilk
'kind' is the definition.
(ilk is a kind of kind)
'of milkman' is the wordplay.
'of' says the answer is hidden in the clue.
'ILK' is hidden in the letters of 'milkman'.
(Other definitions for ilk that I've seen before include "Description" , "A certain type of person" , "Sort or type of silks" , "Of that kind in Kilkenny" , "Of that kind or sort" .)