Good young chap contented (4)
I believe the answer is:
glad
'contented' is the definition.
(I've seen this in another clue)
'good young chap' is the wordplay.
'good' becomes 'g' (abbreviation).
'young chap' becomes 'lad' (I've seen this in another clue).
'g'+'lad'='GLAD'
(Other definitions for glad that I've seen before include "Not sorry" , "More than willing" , "Elated" , "happiness" , "Made up" .)