Cloth is wonderful, almost sumptuous (6)
I believe the answer is:
fabric
'cloth' is the definition.
(I know that cloth can be written as fabric)
'wonderful almost sumptuous' is the wordplay.
'wonderful' becomes 'fab' (slang abbreviation of fabulous).
'almost' means to remove the last letter (most of the word but not all of it).
'sumptuous' becomes 'rich' (similar in meaning).
'rich' with its final letter removed is 'ric'.
'fab'+'ric'='FABRIC'
'is' is the link.
(Other definitions for fabric that I've seen before include "stuff" , "Material in general" , "(Texture of) cloth" , "Woven or knitted material" , "Woven, knitted or felted cloth" .)