The initial idioms of the letter U

under the wing of	under the wire
under the yoke	under the yolk
under water	under way
under glass	underground railroad
underground	underpinnings
understand	understanding
undertake to do	undertow
underwater basket weaving	underwhelm
undies	What's done cannot be undone
unearthly	Uneasy lies the head that wears a crown
unexpected	unexpected always happens
unfamiliar territory	unflappable
unfold into	unfriend
unglued	ungodly
unheard of	unify into