Barriers in sport? (7)
I believe the answer is:
fencing
I believe this is a double definition.
'barriers' is the first definition.
(fencing can mean a set of barriers)
'sport?' is the second definition.
(I've seen this before)
'in' is the link.
(Other definitions for fencing that I've seen before include "Sport with swords" , "Barrier; sport" , "enclosure" , "Olympic sport since 1896" .)