Regret nothing, following heart at last for this (4,4)

'this' is the definition.
I know nothing about this answer so I can't judge whether this works.

'regret nothing following heart at last' is the wordplay.
'regret' becomes 'rue' (to rue something is to regret it).
'nothing' becomes 'love' (love is zero in tennis).
'following' means one lot of letters go next to another.
'at last' suggests the final letters.
The last letter of 'heart' is 't'.
'rue'+'love'='ruelove'
'ruelove' after 't' is 'TRUE-LOVE'.

'for' is the link.

Can you help me to learn more?