There’s very little or nothing in wearing a mat (4)
I believe the answer is:
atom
'there's very little' is the definition.
I can't tell whether this defines the answer.
'nothing in wearing a mat' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'in' means one lot of letters goes inside another.
'wearing' is an anagram indicator (wear can mean to become damaged).
'mat' with letters rearranged gives 'atm'.
'o' placed within 'atm' is 'ATOM'.
'or' is the link.
Can you help me to learn more?
(Other definitions for atom that I've seen before include "A mighty particle, makes huge explosion" , "A tiny powerful particle" , "Minute particle" , "Elementary particle" , "Small particle of matter" .)