Brought up terribly, turn out rude (8)
I believe the answer is:
nurtured
'brought up' is the definition.
('nurture' can be a synonym of 'bring up')
'terribly turn out rude' is the wordplay.
'terribly' indicates anagramming the letters.
'out' indicates an anagram.
'turn' anagrammed gives 'nurt'.
'rude' is an anagram of 'ured'.
'nurt'+'ured'='NURTURED'
(Other definitions for nurtured that I've seen before include "Tended to, a growing child say" , "Fed" , "Fostered" , "Reared" .)