Trade in decimal fractions (4)
I believe the answer is:
deal
'trade in' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for deal that I've seen before include "split deck" , "Distribute cards or do business" , "Soft wood; trade" , "Bargain or kind of wood" , "Pass around (e.g. cards)" .)