Conclude a wall covering is sterile (9)
I believe the answer is:
infertile
'sterile' is the definition.
('infertile' can be similar in meaning to 'sterile')
'conclude a wall covering' is the wordplay.
'conclude' becomes 'infer' (inferring is a kind of concluding).
'a wall covering' becomes 'tile'.
'infer'+'tile'='INFERTILE'
'is' is the link.
(Other definitions for infertile that I've seen before include "Fruitless" , "Barren" , "So can't father" , "Not productive" .)