A judge brought up previously in Bordeaux who is underground drink supplier (7)
I believe the answer is:
aquifer
'underground drink supplier' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'a judge brought up previously in bordeaux who' is the wordplay.
'judge' becomes 'ref'.
'brought up' shows that the letters should be reversed in order (in a down clue, letters go up).
'previously' means one lot of letters go next to another.
'in bordeaux who' becomes 'qui' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ref' back-to-front is 'fer'.
'fer' put after 'qui' is 'quifer'.
'a'+'quifer'='AQUIFER'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for aquifer that I've seen before include "Underground source of water" , "Water-bearing rock formation" , "Rock containing water" , "Water-bearing layer" , "Water-carrying layer of rock" .)