Apparatchik erroneously holds Walker? (5)
I believe the answer is:
hiker
'walker?' is the definition.
(I know that hiker is a type of pedestrian)
'apparatchik erroneously holds' is the wordplay.
'holds' says the answer is hidden in the clue.
'HIKER' is hidden in the letters of 'apparatchik erroneously'.
(Other definitions for hiker that I've seen before include "Someone walking (with backpack?)" , "I could be on the trail" , "Someone who goes on an extended walk for pleasure" , "Rambler" , "Person on long walk" .)