Such boys still have some schooldays! (3)
I believe the answer is:
old
'such boys still' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I can't see?
'some schooldays' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'OLD' is hidden within 'schooldays'.
'have' is the link.
Can you help me to learn more?
(Other definitions for old that I've seen before include "Venerable" , "At an early stage - at a late stage" , "Much-used" , "Long-lived" , "Senescent" .)