For whom Los Angeles is at the back of beyond! (3)
I believe the answer is:
lad
'for' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'los angeles is at the back of beyond' is the wordplay.
'los angeles' becomes 'LA' (abbreviation).
'is at the back of' says to take the final letters (I've seen 'at the back' mean this).
The final letter of 'beyond' is 'd'.
'la'+'d'='LAD'
'whom' acts as a link.
Can you help me to learn more?
(Other definitions for lad that I've seen before include "(Housman's Shropshire) boy" , "Stable employee" , "A young chap into ballads" , "Scottish lover" , "Stable worker" .)