The heavy heart of Glastonbury (3)
I believe the answer is:
ton
'the heavy heart' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'of glastonbury' is the wordplay.
'of' indicates a hidden word.
'TON' is hidden in the letters of 'glastonbury'.
Can you help me to learn more?
(Other definitions for ton that I've seen before include "High-speed" , "A slang 100mph - heavy" , "People of fashion" , "Weight - fashion (French)" , "Heavyweight" .)