I am going to buy a ticket for a concert, and the show description says:
- Door time: 7pm
- Curfew: 10pm
I was thinking that curfew means the latest time you can access the venue, is this correct?
Or does it mean the time the concert will finish?
Learn English – What does “curfew” mean in the context of a concert
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Related Solutions
There is also a political overtone to the use of this phrase. It is not normal to have two responses, one from a party followed by another from a subgroup within that party.
Hence the user of the term may be referring to his belief that this split in the republicans is their entire party's ticket to oblivion. Not just the time-worn habit of the responding speaking being destined to obscurity.
What does “show some (a little) leg” mean in common understanding?
The information you quote from www.wordreference and www.englishforums. com is correct in describing common usage of show some leg or show a little leg. 
The picture above, from It Happened One Night (1934), illustrates a classic example of showing a little leg as a hitchhiking device. Clark Gable brags about his skill at thumbing a ride; lots of cars go by without slowing down at all. Then Claudette Colbert shows some leg and the driver of a passing car brakes as fast as he can and gives Gable and Colbert a lift.
The idiom or imagery in Dowd's sentence probably is easily understood by a large fraction of the US public, and perhaps by other English speakers as well. However, Dowd's sentence has problems: It says Holder is trying to appear benign to put pressure on Sterling, which seems to be a self-contradictory statement. That apparent self-contradiction makes the sentence hard to understand, at least during the first dozen times one reads it.
Does [show some (a little) leg] mean to tempt a desired reaction from the other, or to reveal one’s real intention? Is it a common phrase?
It ordinarily is understood as temptation, rather than as a way of revealing one’s real intention, although when Mrs. Robinson in The Graduate shows some leg, it both reveals her intention and acts as a temptation.
Ngrams for show some leg,show a little leg suggests both phrases have greatly increased in popularity since the 1980s, so proper understanding of the phrases probably is widespread.
Best Answer
Literally it means "A regulation requiring certain or all people to leave the streets or be at home at a prescribed hour" or "the time at which such a restriction begins or is in effect"Merriam-Webster usually because of political instability in a certain country or province. Here, in the context of a concert it means:
That is, the concert is suposed to be over by 10 pm.