There's something dry about the Tower of London (4)
I believe the answer is:
moat
'tower of london' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'there's something dry about the' is the wordplay.
I cannot really understand how this works, but
'about' could be 'a' (abbreviation in Chambers) and 'a' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'mo' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for moat that I've seen before include "Water around castle" , "A deep water-filled ditch around a castle" , "Water-filled trench around a castle" , "Water-filled defensive trench" , "Water crossed via a drawbridge" .)