Getting out of bed with a bellow causes a riot (6)
I believe the answer is:
uproar
'riot' is the definition.
(I've seen this in another clue)
'getting out of bed with a bellow' is the wordplay.
'getting out of bed' becomes 'up' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' is a charade indicator (letters next to each other).
'a bellow' becomes 'roar' (synonyms).
'up'+'roar'='UPROAR'
'causes a' is the link.
Can you help me to learn more?
(Other definitions for uproar that I've seen before include "Tumult and bedlam" , "Lots of angry noise" , "Outbreak of noisy and boisterous behaviour" , "Rumpus" , "Turmoil" .)