Answer: GAPER

AnswerCrossword Clue
GAPERBurrowing clam
gaperperson or thing that gapes
gaperlarge clam, Tresus capax, common on gravelly and coarse-sand beaches
gaperone that gapes (to stare with open mouth)
GAPERShe's awed
GAPERStunned eyewitness, obviously
GAPERGawker
GAPEROne with a wide-open mouth
GAPERWowed eyewitness
GAPERSlack-jawed one
GAPEROne who's starstruck
GAPERLarge clam
GAPEROne yawning
GAPERType of large clam
GAPERAwed chap
GAPERRubbernecker
GAPERHe shows surprise
GAPEROpenmouthed one
GAPEROpen-mouthed one
GAPEROne who stares
GAPERDumfounded onlooker.
GAPERCurious one.
GAPERAmazed onlooker.
GAPERAstonished one.
GAPERCurious bystander.
GAPERSleepy one.
GAPERYawner.
GAPERAwestruck one
GAPERAwestruck tourist, e.g.