Company concerned with change (4)
I believe the answer is:
coin
'change' is the definition.
(I've seen this in another clue)
'company concerned with' is the wordplay.
'company' becomes 'co' (abbreviation).
'concerned with' becomes 'in' (I've seen this in other clues).
'co'+'in'='COIN'
(Other definitions for coin that I've seen before include "Think up" , "Metal money disc" , "Invent a word or phrase - for money?" , "Fabricate" , "Invent (a new phrase)" .)