Suit's suit shows deepest affection (5,2,6)

'deepest affection' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'suit's suit' is the wordplay.
I cannot really understand how this works, but
'suit's' could be 'hearts' and 'hearts' is located in the answer.
'suit' could be 'heart' and 'heart' is found in the answer.
The remaining letters 'of' 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).

'shows' acts as a link.

Can you help me to learn more?