The initial idioms of the letter O

to the teeth	one's walking papers
one's way	one's way of life
one's word is bond	one's work is cut out for one
oneself	get together
one-shot	one-track mind
one-up (someone)	onion
online	only
only daughter	only fools and horses work
only game in town, the	only have eyes for
only just	only Nixon could go to China
only son	only the good die young
only too	only way to go
on	on-target
onto	onto a good thing
onto someone/something	ontogeny recapitulates phylogeny