How one's brethren are beloved (6)
I believe the answer is:
dearly
'beloved' is the definition.
(thesaurus)
'how one's brethren are' is the wordplay.
I cannot quite see how this works, but
an anagram of 'are' is 'ear' which is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dearly that I've seen before include "How I love my wife" , "Very much; at great cost" , "paying for big mistakes like this!" , "At a high price - with fondness" , "With affection - at great cost" .)