Nigel almost bamboozled mum in puzzle (6)
I believe the answer is:
enigma
'puzzle' is the definition.
(I've seen this in another clue)
'nigel almost bamboozled mum' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'bamboozled' is an anagram indicator (I've seen this in other clues).
'mum' becomes 'ma' (ma can mean mother).
'nigel' with its final letter taken away is 'nige'.
'nige' with letters rearranged gives 'enig'.
'enig'+'ma'='ENIGMA'
'in' acts as a link.
(Other definitions for enigma that I've seen before include "Gamine being a bit of a puzzle" , "Mysterious person" , "Elgar Variations nickname" , "Mysterious person/thing" , "It's mysterious like gamine" .)