Photo-hosting website (6)
I believe the answer is:
flickr
(Another definition for flickr that I've seen is " Where to see 21 [PHOTO]s".)
I've seen this clue in the Universal.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free.
Check out my app
or
learn more
about the Crossword Genius project.