What holds water in a raised lock, not following English river (7)
I believe the answer is:
aquifer
'what holds water in' is the definition.
(rock which can contain water)
'a raised lock not following english river' is the wordplay.
I cannot really see how this works, but
'a' is present in the answer.
'following' could be 'f' (used when citing page numbers etc) and 'f' is located in the answer.
'english' could be 'e' (abbreviation) and 'e' is located in the answer.
'river' could be 'r' and 'r' is located in the answer.
This explanation may well be incorrect...
(Other definitions for aquifer that I've seen before include "Water-bearing stratum of permeable rock" , "Water-carrying layer of rock" , "Water-bearing rock formation" , "it holds water" , "Underground source of water" .)