Pace of trade varies (5)
I believe the answer is:
tread
'pace' is the definition.
(I know that pace can be written as tread)
'trade varies' is the wordplay.
'varies' is an anagram indicator.
'trade' is an anagram of 'TREAD'.
'of' is the link.
(Other definitions for tread that I've seen before include "Top surface of a stair step" , "Stomp heavily" , "Press (grapes by foot)" , "Surface of car tyre" , "Grooves on tyre" .)