Fabric made out of sweet william (5)
I believe the answer is:
twill
'fabric' is the definition.
(type of fabric)
'out of sweet william' is the wordplay.
'out of' indicates a hidden word.
'TWILL' can be found hidden inside 'sweet william'.
'made' acts as a link.
(Other definitions for twill that I've seen before include "Fabric with distinctive weave" , "Cloth with diagonal ribs" , "Fabric woven to produce a surface of diagonal parallel ridges" , "Strong ridged fabric" , "Diagonal-weave fabric" .)