Day ends in anger for brother (5)
I believe the answer is:
friar
'for brother' is the definition.
(I've seen this in another clue)
'day ends in anger' is the wordplay.
'day' becomes 'fri' (abbreviation for Friday).
'ends in anger' becomes 'ar' (I can't justify this - if you can you should give a lot more credence to this answer).
'fri'+'ar'='FRIAR'
Can you help me to learn more?
(Other definitions for friar that I've seen before include "Mendicant preacher" , "Religious man" , "Religious brother" , "Member of one of the four mendicant orders" , "Mendicant monk" .)