Routine in public transport for Roman conspirator (6)
I believe the answer is:
brutus
'roman conspirator' is the definition.
(I've seen this before)
'routine in public transport' is the wordplay.
'routine' becomes 'rut' (being stuck in a rut is being stuck in a routine).
'in' means one lot of letters goes inside another.
'public transport' becomes 'bus' (bus is a kind of public transport).
'rut' going into 'bus' is 'BRUTUS'.
'for' is the link.
(Other definitions for brutus that I've seen before include ""The noblest Roman of them all"" , "One of Caesar's killers" , "Caesar's assassin" , "Murderer of Caesar" , "senator in Rome once" .)