Obstacle arranged to block coffin bearer (7)
I believe the answer is:
barrier
'obstacle' is the definition.
(barrier is a kind of obstacle)
'arranged to block coffin bearer' is the wordplay.
'arranged' becomes 'arr' (abbreviation).
'to block' indicates putting letters inside (block can mean to plug a gap).
'coffin bearer' becomes 'bier' (I can't explain this - if you can you should believe this answer much more).
'arr' inserted inside 'bier' is 'BARRIER'.
Can you help me to learn more?
(Other definitions for barrier that I've seen before include "Boom" , "Construction to contain, say, crowds" , "it's soundly broken!" , "Impediment" , "Gate" .)