As brave as a lion: very brave.
“My young daughter is as brave as a lion and will tackle any of the boys in rough-and-tumble games.”
Lion-hunter: somebody who seek the friendship of famous people.
“Mervin is a typical lion-hunter; he gets himself invited to the publishers’ parties so that he can meet all the top authors.”
Lion’s share: biggest part.
“There were three of us helping but I found myself doing the lion’s share of the work.”
Put one’s head in the lion’s mouth: adopt a position that is dangerous/risky.
“I’ll have to put my head in the lion’s mouth and ask my husband if I can go to the hen party on the evening before Dora’s wedding.”
Throw somebody to the lions: endanger somebody (to save oneself).
“The supervisor has given me extra responsibility, but warned me that if I make a mistake she’ll throw me to the lions.”
(From John O.E. Clark, Dictionary of English Idioms, Harrap’s)
