A little matter one gets ahead with (3)
I believe the answer is:
ion
'a little matter' is the definition.
'ion' can be an answer for 'matter' (ion is a kind of matter). I'm not certain of the 'a little' bit.
'one gets ahead with' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
'ahead' could be 'on' (synonyms) and 'on' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ion that I've seen before include "Electrically-charged particle" , "Eletrically charged particle" , "Subatomic particle" , "Charged atom/molecule" , "Electrically charged atom or group of atoms" .)