Ask to come here for a reading of the odds? (4-4)

'the odds?' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'ask to come here for a reading' is the wordplay.
'ask' becomes 'call' (calling is a kind of asking).
'to come here' becomes 'ove' (I am not sure about this - if you are sure you should believe this answer much more).
'for' is a charade indicator (letters next to each other).
'a reading' becomes 'r' (one of the traditional three R's of education).
'call'+'ove'+'r'='CALL-OVER'

'of' acts as a link.

Can you help me to learn more?