Antonio's heavy heart (3)
I believe the answer is:
ton
'heavy heart' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'antonio's' is the wordplay.
'TON' is hidden in amongst the letters.
However, I am not sure how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for ton that I've seen before include "1000 kilos" , "Two thousand - two hundred and forty pounds" , "Twenty cwt" , "Fashionable" , "People of fashion" .)