Answer:

GASP

Answer	Crossword Clue
GASP	Reaction of surprise
GASP	Express surprise
GASP	Post-aerobics breath, perhaps

GASP	Shocked reaction
GASP	Shocking reaction
GASP	Breathe laboriously
GASP	Wheeze
GASP	Pant
GASP	Sound from one who was underwater too long
GASP	Shocked sound
GASP	["I'm shocked!"]

GASP	Sound of surprise
GASP	Show shock
GASP	Struggle for breath
GASP	React with shock
GASP	Show sharp shock
GASP	React in horror
GASP	Appear wowed
GASP	Quickly inspire

GASP	Sound made upon surfacing
GASP	Reaction to a revelation
GASP	Struggle for air
GASP	Breathe hard
GASP	Rapid intake
GASP	Shocked response
GASP	Show surprise
GASP	Stunned sound

GASP	[How shocking!]
GASP	Slack-jawed reaction
GASP	[Oh, my!]
GASP	[I'm shocked!]
GASP	Sound of shock
GASP	Sudden intake
GASP	[Oh, no!]
GASP	Response to a shock

GASP	[Horrors!]
GASP	Astonished reaction
GASP	Fight for air
GASP	[Heavens!]
GASP	[Oh my God!]