The Democratic nominee leads Trump 45% to 40% among likely voters, with Libertarian Gary Johnson receiving 6% of voter support and Green Party nominee Jill Stein getting 3%.
Nearly half -- 46% -- of independent voters are backing the Democratic candidate while just under a third -- 32% -- of independent voters are backing Trump. Johnson gets 10% of their vote.
The poll, conducted after Tuesday's vice presidential debate, marks a climb for Clinton after Quinnipiac's most recent poll on September 26, when she was clinging to a 1 point advantage over Trump.
In that survey, independents were backing Trump 42% to Clinton's 35%, with 15% behind Johnson.
"With her base of women and non-white voters now solidly behind her and independent voters moving into her column, Donald Trump gets a wake-up call," said Tim Malloy, assistant director of the Quinnipiac University Poll. "The Indies are leaving in droves."
Among women voters, the Democratic nominee has a 20 point lead and a 45 point lead among voters of color over the businessman to give Clinton a 5-point lead over Trump.
In a head-to-head match-up, Clinton has half of the female vote while Trump wins 44%.
In a four-way race, 53% of women back Clinton while Trump gets 33% of the female vote. Nearly half -- 49% -- of men are backing Trump while 37% support Clinton.
Slightly more than half -- 51% -- of white voters are backing Trump while Clinton has the support of 63% of non-white voters.
Forty-eight percent of likely millennial voters are supporting Clinton, with 27% of voters aged 18 to 34 backing Trump.
Johnson has 11% of the millennial vote and Stein has 9%.
The poll was conducted from October 5 to 6 and surveyed 1,064 likely voters nationwide. There is a margin of error of +/- 3 percentage points. Live interviewers called landlines and cell phones.