Real trouble upset Ophelia's brother (7)
I believe the answer is:
laertes
'ophelia's brother' is the definition.
(I've seen this before)
'real trouble upset' is the wordplay.
'trouble' indicates an anagram.
'upset' becomes 'tes' (I've seen this in other clues**).
'real' anagrammed gives 'laer'.
'laer'+'tes'='LAERTES'
(Other definitions for laertes that I've seen before include "Son of Polonius (Hamlet)" , "Greek king" , "... killer of prince" , "Man advised not to borrow" , "Brother of Ophelia (Hamlet)" .)