So blue after first love's gone off the boil (4)
I believe the answer is:
slow
'so blue' is the definition.
Both the definition and answer are adjectives. Maybe there's a link between them I don't understand?
'first love's gone off the boil' is the wordplay.
I cannot quite see how this works, but
'first' could be 'low' (synonyms) and 'low' is found in the answer.
A single letter 's' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'after' is the link.
Can you help me to learn more?
(Other definitions for slow that I've seen before include "Crawling" , "Taking a long time" , "Behind time" , "Leisurely" , "Lacking in pace or interest" .)