A superior letter to the Standard, from Jacob's brother (4)
I believe the answer is:
esau
'jacob's brother' is the definition.
(I've seen this in another clue)
'a superior letter to the standard from' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
'superior' could be 'u' (U can mean upper-class, as in U and non-U speech) and 'u' is present in the answer.
'letter' could be 's' and 's' is found in the answer.
'from' could be 'e' (I've seen this in other clues) and 'e' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for esau that I've seen before include "man tricked by kid brother" , "He traded his birthright for a mess of pottage" , "brother done in Bible" , "Hairy OT character" , "Jacob's twin (Bible)" .)