Love of the past (3,5)
I believe the answer is:
old flame
'the past' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I don't see?
'love' is the wordplay.
I cannot really see how this works, but
'love' could be 'flame' (I've seen this before) and 'flame' is found within the answer.
The remaining letters 'old' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for old flame that I've seen before include "Ex-lover - the fire still burns" , "Someone once loved" , "still 1 across [ALIGHT], it seems" , "Ex" , "Former partner" .)