Dislodge hobo sitting on top of pillar (4)
I believe the answer is:
bump
'dislodge' is the definition.
('bump' can be a synonym of 'dislodge')
'hobo sitting on top of pillar' is the wordplay.
'hobo' becomes 'bum' ('bum' can be a synonym of 'hobo').
'sitting on' says to put letters next to each other.
'top of' says to take the initial letters.
The first letter of 'pillar' is 'p'.
'bum'+'p'='BUMP'
(Other definitions for bump that I've seen before include "Knock - collide" , "little impact" , "Impact injury" , "Collide with force or violence" , "Swelling caused by a blow perhaps" .)