Bad-tempered youth's first after examination (5)
I believe the answer is:
testy
'bad-tempered' is the definition.
(thesaurus)
'youth's first after examination' is the wordplay.
'youth's first' becomes 'y' (I can't explain this - if you can you should give a lot more credence to this answer).
'after' is a charade indicator (letters next to each other).
'examination' becomes 'test' ('test' can be a synonym of 'examination').
'y' after 'test' is 'TESTY'.
Can you help me to learn more?
(Other definitions for testy that I've seen before include "snappy" , "Grumpy" , "Irritable" , "likely to flare up?" , "Showing irritation" .)