Young lads sharing a house perhaps, hopefully in good form (10)
I believe the answer is:
schoolboys
'sharing a house perhaps hopefully in good form' is the definition.
I can't judge whether this definition defines the answer.
'young lads' is the wordplay.
'young' becomes 'school' (I can't explain this - if you can you should give a lot more credence to this answer).
'lads' becomes 'boys' (I've seen this in another clue).
'school'+'boys'='SCHOOLBOYS'
Can you help me to learn more?
(Another definition for schoolboys that I've seen is " pupils".)