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.
Perhaps 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 found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
The remaining letters 'mo' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
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" .)