Magazine copy editor. Not reporter, or publisher, or photographer – copy editor.
Dentist: “Eversmile, New Jersey” (Daniel Day-Lewis)
Insurance underwriter: “Double Indemnity” maybe? Did he do any underwriting?
Waiter: “Waiting” (Ryan Reynolds comedy)
Printing press operator: not a film, but there’s Gutenberg! The Musical! I’d be surprised if there weren’t a film out there about Gutenberg, though.
Young Warriors. Featured some pretty trippy animation, too.
Close to this would be Kenny, in which the central character’s profession is renting out and installing portable toilets. It’s a very funny movie, but I don’t think it’s known much outside Australia.
Optometrist. Very common profession, yet somehow not very well represented in movies, at least among lead roles.
I daresay there are very few films about musical orchestration. Not composers, conductors or musicians, but orchestrators.
One Hour Photo. He wasn’t a pharmacist. His character worked in the photo lab, developing the pictures.
Trees Lounge. Except Steve Buscemi’s character was out of work most of the time.
Double Indemnity featured an insurance agent and an insurance investigator (played respectively by Fred MacMurray and Edward G. Robinson) as pivotal characters. Also, Guy Pearce’s character (Leonard Shelby) in Memento was an insurance investigator who quit due to short-term memory problems. I don’t know if those examples are close enough for you.
Double Indemnity.
Edit: NDP beat me to it. Forgot about Memento.
Insurance adjustors are represent the female leads in both versions of The Thomas Crown Affair.
Ha!
And in the anime Trigun the female leads Meryl Stryfe and Milly Thompson are employees of the Bernardelli Insurance Society.
Not an underwriter, but there is a movie by Atom Egoyan called The Adjuster. Is that close enough?
Drew Barrymore’s character in Never Been Kissed is a copy editor, although, I think, for a newspaper.
Who beat you to it? <casts furtive glance upthread>
In Benny and Joon, Benny (Aidan Quinn) and his best friend are auto mechanics.
How about a historian?
If that includes archaeologists, there’s practically an entire subgenre of fedora-ed, whip toting historians in the “Action” section of your local movie store. 
I think there’s only been one movie that starred a technical writer. If memory serves, the movie was called The Technical Writer. That’s a title that’ll bring them in.