Burn unit young characters aid (7)
I believe the answer is:
charity
'aid' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'burn unit young characters' is the wordplay.
'burn' becomes 'char' (charring is a kind of burning).
'unit' becomes 'I' (resembles t, a unit).
'young characters' becomes 'ty' (I can't justify this - if you can you should believe this answer much more).
'char'+'i'+'ty'='CHARITY'
Can you help me to learn more?
(Other definitions for charity that I've seen before include "Act of giving to those in need" , "Fund" , "Almsgiving" , "Love" , "Help for needy" .)