Sour, loveless and redundant (7)
I believe the answer is:
surplus
'redundant' is the definition.
(I know that redundant can be written as surplus)
'sour loveless and' is the wordplay.
I cannot quite see how this works, but
'and' could be 'plus' and 'plus' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for surplus that I've seen before include "unnecessary" , "Redundant" , "(An) oversupply" , "Remainder" , "Extra to requirements" .)