A clever remark backfiring a bit? (4)
I believe the answer is:
atom
'a bit?' is the definition.
(I have seen 'Tiny bit' mean 'atom' so perhaps 'bit' could also mean 'atom')
'a clever remark backfiring' is the wordplay.
'clever remark' becomes 'mot' (I've seen this before).
'backfiring' says the letters should be written in reverse.
'mot' backwards is 'tom'.
'a'+'tom'='ATOM'
(Other definitions for atom that I've seen before include "A mighty particle, makes huge explosion" , "Nucleus plus electrons" , "An explosive particle as in bomb" , "Piece of matter in moat" , "type of bomb" .)