Vagrant putting pressure on public transport (5)
I believe the answer is:
tramp
'vagrant' is the definition.
(thesaurus)
'pressure on public transport' is the wordplay.
'pressure' becomes 'p' (abbreviation).
'on' is a charade indicator (letters next to each other).
'public transport' becomes 'tram' (I've seen this before).
'p' put after 'tram' is 'TRAMP'.
'putting' is the link.
(Other definitions for tramp that I've seen before include "Itinerant" , "Walk heavily - steamer" , "Attack with knife" , "Take a walk" , "I usually walk" .)