Adolescent brewed green tea (8)
I believe the answer is:
teenager
'adolescent' is the definition.
(I know that adolescent can be written as teenager)
'brewed green tea' is the wordplay.
'brewed' indicates anagramming the letters.
'green'+'tea'='greentea'
'greentea' anagrammed gives 'TEENAGER'.
(Other definitions for teenager that I've seen before include "troublesome youth" , "hormonal problem?" , "Old child or young adult?" , "Young person" , "Generate (anag)" .)