Annoying being stopped by a barrier (7)
I believe the answer is:
railing
'barrier' is the definition.
(I know that railing is a type of barrier)
'annoying being stopped by a' is the wordplay.
'annoying' becomes 'riling' ('rile' can be a synonym of 'annoy').
'being stopped by' indicates putting letters inside (stopping can mean blocking a gap).
'riling' enclosing 'a' is 'RAILING'.
(Other definitions for railing that I've seen before include "Iron barrier" , "Protesting (about); fence" , "barrier appears" , "Complaining bitterly - barrier" , "Haranguing -- horizontal bar on supports" .)