'water?' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'model t ford covered by founder' is the wordplay.
'model' indicates an anagram (the solver must model the letters into a new form).
'covered by' means one lot of letters goes inside another.
'founder' becomes 'sink' (sinking is a kind of foundering).
't'+'ford'='tford'
'tford' with letters rearranged gives 'oftdr'.
'oftdr' placed inside 'sink' is 'SOFT DRINK'.
'in' is the link.
Can you help me to learn more?
(Other definitions for soft drink that I've seen before include "Eg, lemonade" , "Don't frisk about with non-alcoholic beverage" , "Perhaps, cordial" .)