Block robust exchange on court (8)
I believe the answer is:
obstruct
'block' is the definition.
(I know that block can be written as obstruct)
'robust exchange on court' is the wordplay.
'exchange' is an anagram indicator.
'on' means one lot of letters go next to another.
'court' becomes 'ct' (abbreviation used in road names).
'robust' with letters rearranged gives 'obstru'.
'obstru'+'ct'='OBSTRUCT'
(Other definitions for obstruct that I've seen before include "Impede - block" , "Hinder or impede" , "Get in the way of" , "Hamper" , "Prevent or hinder movement" .)