To some extent young (3)
I believe the answer is:
ten
'young' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?
'to some extent' is the wordplay.
'to some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'TEN' is hidden in the letters of 'extent'.
Can you help me to learn more?
(Other definitions for ten that I've seen before include "How many" , "Five times two" , "Cardinal number" , "Base of decimal system" , "Very young" .)