Fix tariff charges basically for trade (7)
I believe the answer is:
traffic
'trade' is the definition.
(trafficking is a kind of trading)
'fix tariff charges basically' is the wordplay.
'fix' indicates anagramming the letters.
'basically' says to take the initial letters (the first letter could be its root or base).
The initial letter of 'charges' is 'c'.
'tariff' is an anagram of 'traffi'.
'traffi'+'c'='TRAFFIC'
'for' is the link.
(Other definitions for traffic that I've seen before include "Deal in, trade" , "Dishonest trading" , "Business" , "Vehicles moving on public highways" , "Moving vehicles; trade" .)