Here are the first five searches for the phrase “liberal Hollywood” on the New York Times site, as sorted by oldest:

1. Jan. 28, 1975: “He is also consulting with Warren Beatty and other liberal Hollywood stars who backed Senator George McGovern for the 1972 nomination.” — from Christopher Lydon's straightforward “Special to the Times” piece on Henry “Scoop” Jackson considering a run for president in 1976.
2. Oct. 7, 1990: “He has won wide admiration among Jews for his staunch support for Israel and has earned credits in traditionally liberal Hollywood circles for backing the motion picture industry in its regulatory battle with the television networks over syndication of reruns.” — from Robert Reinhold's straightforward “Special to the Times” piece on California gubernatorial candidate Pete Wilson steering a course for the political center. 
3. Oct. 26, 1990: “Citing contributions to Mr. Waite from Al Pacino and other movie figures, Mr. McCandless said that Mr. Waite is part of the 'liberal Hollywood crowd'...” — from Robert Reinhold's “Special to the Times” piece on conservative U.S. Rep. Al McCandless' poliltical battle with actor Ralph Waite, who played Pa Walton on “The Waltons” in the 1970s. 
4. Sept. 17, 1991: “'[Bob] Kerrey's the one in the liberal Hollywood community,' said one influential public relations executive who spoke on condition of anonymity. 'He's spent a lot of time out here. Frankly, he's young, he's attractive, he's a war hero, he slept with a movie star and he's got a good hair cut.'” — from Bernard Weinraub's piece on Hollywood's love of gossip, including, but not limited to, the 1992 presidential election. 
5. June 25, 1992: “Perotmania seems to be hitting liberal Hollywood, at least somewhat.” — from Bernard Weinraub's gossip column on budgets and the '92 campaign. 

Over time, the compound modifier becomes its own phrase. Then it's off to the races.