Pursues one side of the coin (5)
I believe the answer is:
tails
I believe this clue is a double definition.
'pursues' is the first definition.
(tailing is a kind of pursuing)
'one side of the coin' is the second definition.
(I've seen this in another clue)
(Other definitions for tails that I've seen before include "as opposed to heads" , "Full evening dress for men" , "the back of bears - bulls too" , "Evening dress; coin toss call" , "Ends" .)