Obstruct a claim pedestrians are holding (6)
I believe the answer is:
impede
'obstruct' is the definition.
(I know that obstruct can be written as impede)
'a claim pedestrians are holding' is the wordplay.
'are holding' says the answer is hidden in the clue.
'IMPEDE' is hidden in the letters of 'claim pedestrians'.
(Other definitions for impede that I've seen before include "Bar" , "Hamper" , "Hinder, be obstructive" , "Obstruct, hold up progress" , "Obstruct or thwart" .)