Youth keen to grasp German finally after half term (8)
I believe the answer is:
teenager
'youth' is the definition.
(I've seen this before)
'keen to grasp german finally after half term' is the wordplay.
'keen' becomes 'eager' (I've seen this before).
'to grasp' means one lot of letters goes inside another.
'finally' indicates one should take the final letters.
'after' is a charade indicator (letters next to each other).
'half' means to take half the letters.
The last letter of 'german' is 'n'.
'eager' placed around 'n' is 'enager'.
'term' halved is 'te'.
'enager' after 'te' is 'TEENAGER'.
(Other definitions for teenager that I've seen before include "Young person" , "troublesome youth" , "Youngster" , "one with an unpredictable nature" , "Adolescent" .)