Lecturer betting on each king and queen (7)
I believe the answer is:
speaker
'lecturer' is the definition.
(I've seen this before)
'betting on each king and queen' is the wordplay.
'betting' becomes 'sp'.
'on' is a charade indicator (letters next to each other).
'each' becomes 'ea' (abbreviation).
'king and queen' becomes 'ker' (K for King and ER for Elizabeth Regina).
'sp'+'ea'+'ker'='SPEAKER'
(Other definitions for speaker that I've seen before include "Person presiding over British House of Commons or similar assembly" , "Michael Martin MP" , "One in pulpit, say" , "He asks for order" , "audio equipment" .)