Material is kind on skin at first (4)
I believe the answer is:
silk
'material' is the definition.
(silk is a kind of material)
'kind on skin at first' is the wordplay.
'kind' becomes 'ilk' (ilk is a kind of kind**).
'on' means one lot of letters go next to another.
'at first' says to take the initial letters.
The first letter of 'skin' is 's'.
'ilk' put after 's' is 'SILK'.
'is' is the link.
(Other definitions for silk that I've seen before include "Fabric obtained from the cocoon of a worm" , "Ancient double-oared ship could be mire" , "Item of fine legwear" , "Rich fabric" , "Lustrous fibre" .)