Be next to a judge overwhelmed by murder (6)
I believe the answer is:
adjoin
'be next to' is the definition.
(to adjoin is to be next to something)
'a judge overwhelmed by murder' is the wordplay.
'judge' becomes 'j' (abbreviation for judge).
'overwhelmed by' means one lot of letters goes inside another (I've seen this in other clues).
'murder' becomes 'do in' ('do in' can mean to kill).
'j' placed within 'doin' is 'djoin'.
'a'+'djoin'='ADJOIN'
(Other definitions for adjoin that I've seen before include "Be next to (something)" , "Butt up against" , "Be next or nearest to" , "Lie next to" , "20 down" .)