Run over on joining head of funeral cortege (8)
I believe the answer is:
rehearse
'run over' is the definition.
(I've seen this before)
'on joining head of funeral cortege' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'joining' says to put letters next to each other.
'head of funeral cortege' becomes 'hearse'.
're'+'hearse'='REHEARSE'
(Other definitions for rehearse that I've seen before include "prepare for performance" , "Run through (a play)" , "What actor does to prepare for play" , "Practice for the performance" , "Practise (one's lines)" .)