One very particular about things in song and dance fund (7)
I believe the answer is:
fusspot
'one very particular about things' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'song and dance fund' is the wordplay.
'song' becomes 'fuss' (e.g. to make a song (and dance) about something).
'and' says to put letters next to each other.
'dance fund' becomes 'pot' (I can't justify this - if you can you should give a lot more credence to this answer).
'fuss'+'pot'='FUSSPOT'
'in' is the link.
Can you help me to learn more?
(Other definitions for fusspot that I've seen before include "Nervously agitating type" , "Over-fastidious person" , "Pernickety person" , "One who gets worked up" , "one worrying about trifles" .)