Fabric cut: it is seen in a soft glow (6)
'seen in a soft glow' is the definition.
(twilit means illuminated at twilight)
'fabric cut it' is the wordplay.
'fabric' becomes 'twill' (type of fabric).
'cut' means to remove the last letter.
'twill' with its final letter taken away is 'twil'.
'is' is the link.
(Other definitions for twilit that I've seen before include "in the dusk", "Road surfacing", "Not being fully illuminated", "in the gloom", "Dimly illuminated".)