Tread nervously in business (5)
I believe the answer is:
trade
'business' is the definition.
(I know that trade is a type of business)
'tread nervously' is the wordplay.
'nervously' indicates anagramming the letters.
'tread' anagrammed gives 'TRADE'.
'in' acts as a link.
(Other definitions for trade that I've seen before include "Barter, do business" , "Buy and sell in business" , "Commercial exchange of goods and services" , "job" , "Transaction" .)