Puzzle from mischievous child given tremendous backing (6)
I believe the answer is:
baffle
'puzzle' is the definition.
(baffle can mean to puzzle)
'mischievous child given tremendous backing' is the wordplay.
'mischievous child' becomes 'elf' (I've seen this in another clue).
'given' means one lot of letters go next to another.
'tremendous' becomes 'fab' (fab is short for fabulous).
'backing' says the letters should be written backwards.
'elf'+'fab'='elffab'
'elffab' reversed gives 'BAFFLE'.
'from' is the link.
(Other definitions for baffle that I've seen before include "Mystify, flummox" , "Perplex and bewilder" , "Puzzle and perplex" , "Damper - foil" , "Dumbfound" .)