Where there's just one fowl on the water (7)
I believe the answer is:
swansea
'where' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'just one fowl on the water' is the wordplay.
'just one fowl' becomes 'swans' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'the water' becomes 'ea' (I've seen this in other clues).
'swans'+'ea'='SWANSEA'
'there's' acts as a link.
Can you help me to learn more?
(Other definitions for swansea that I've seen before include "coastal location" , "South Wales city" , "Welsh city" , "Birthplace of Dylan Thomas" , "South Wales port" .)