Calls about trouble in barrier (8)
I believe the answer is:
railings
'calls about trouble in barrier' is the definition.
I can't tell whether this defines the answer.
'calls about trouble' is the wordplay.
'calls' becomes 'rings' ('ring' can be a synonym of 'call').
'about' means one lot of letters goes inside another.
'trouble' becomes 'ail' (synonyms).
'rings' placed around 'ail' is 'RAILINGS'.
Can you help me to learn more?
(Other definitions for railings that I've seen before include "bitter complaints" , "Iron bars set into protective fence" , "Protective barriers" , "Fences of upright metal bars, often around parks" , "Metal guards" .)