University heads gambling, for example, on probability with second roll-over (4,11)

'university heads' is the definition.
'vice chancellors' can be an answer for 'heads' (vice chancellor is a kind of head). I'm not sure about the 'university' bit.

'gambling for example on probability with second roll-over' is the wordplay.
'gambling for example' becomes 'vice' (gambling is a kind of vice).
'on' says to put letters next to each other.
'probability' becomes 'chance' (synonyms).
'with second roll over' becomes 'llors' (I can't explain this - if you can you should give a lot more credence to this answer).
'vice'+'chance'+'llors'='VICE CHANCELLORS'

Can you help me to learn more?