Product of cows from meadow yonder? Not entirely (7)
I believe the answer is:
leather
'product of cows' is the definition.
'meadow yonder? not entirely' is the wordplay.
'meadow' becomes 'lea' (I've seen this before).
'yonder?' becomes 'there' (I've seen this before).
'not entirely' means to remove the last letter.
'there' with its last letter removed is 'ther'.
'lea'+'ther'='LEATHER'
'from' is the link.
(Other definitions for leather that I've seen before include "Dressed hide" , "Treated hide" , "Fabric" , "kid, say" , "kid, perhaps" .)