Train: concerning transport for those who are late? (8)
I believe the answer is:
rehearse
'train' is the definition.
(I've seen this before)
'concerning transport for those who are late?' is the wordplay.
'concerning' becomes 're'.
'transport for those who are late?' becomes 'hearse'.
're'+'hearse'='REHEARSE'
(Other definitions for rehearse that I've seen before include "Run through (a play)" , "Practise before a public performance" , "Train" , "Practice in theatre" , "Practise (one's lines)" .)