Public transport broken — time’s lost (3)
I believe the answer is:
bus
'public transport' is the definition.
(bus is a kind of public transport)
'broken time's lost' is the wordplay.
'broken' becomes 'bust' (bust can mean broken).
'time' becomes 't' (abbreviation).
'lost' is a deletion indicator.
'bust' with 't' taken out is 'BUS'.
(Other definitions for bus that I've seen before include "People carrier" , "Of projectiles; (go) mad (slang)" , "Coach" , "Public transport vehicle" , "Something caught" .)