So let cabs go around these barriers (9)
I believe the answer is:
obstacles
'these barriers' is the definition.
(I've seen this before)
'so let cabs go' is the wordplay.
'go' indicates an anagram (I've seen 'went' mean this ('go' can mean move)).
'so'+'let'+'cabs'='soletcabs'
'soletcabs' anagrammed gives 'OBSTACLES'.
'around' is the link.
(Other definitions for obstacles that I've seen before include "These block" , "Hindrances, impediments" , "hurdles" , "bars" , "barriers" .)