Crossword puzzle clue "cake often seen in a dish"

Cake often seen in a dish

Something often seen on a street corner, briefly ... or, literally, something seen in each corner of this puzzle

"The cake is ___" (graffito seen in the game "Portal"): 2 wds.

Spiro who wrote, "If you've seen one city slum, you've seen them all"

Springsteen "If you've ever seen ___ trick pony then you've seen me"

Feeling that you've seen something before seen something before

"If you've ___ seen a one-trick pony, then you've seen me"

"If you haven't seen ___, you haven't seen New York" (old ad slogan)