Morning rush hour perhaps not a matter for debate (5,3,6)
I believe the answer is:
early day motion
'not a matter for debate' is the definition.
(type of UK parliamentary motion)
'morning rush hour perhaps' is the wordplay.
'morning' becomes 'earlyday'.
'rush hour perhaps' becomes 'motion' (I can't justify this - if you can you should believe this answer much more).
'earlyday'+'motion'='EARLY DAY MOTION'
(Other definitions for early day motion that I've seen before include "what MPs rarely debate" , "It's seldom discussed in Parliament" , "parliamentary item" , "Parliamentary proposal" , "Evacuation at dawn" .)