German fellow’s happiness (4)
I believe the answer is:
glee
'happiness' is the definition.
(I know that glee is a type of gaiety)
'german fellow's' is the wordplay.
'german' becomes 'g' (abbreviation).
'fellow' becomes 'lee' (I can't justify this - if you can you should believe this answer much more).
'g'+'lee'='GLEE'
Can you help me to learn more?
(Other definitions for glee that I've seen before include "Part song for men" , "Unholy mirth or triumphant joy" , "Old English part-song" , "Mirth - part song for male voices" , "Merriment or gloating" .)