ADJ

small
hinged
loose
a loose flap of skin
tent
pocket
a stylish jacket with leather cuffs and pocket flaps

VERB + FLAP

undo
The officer undid the flap of his holster and drew his gun
draw back, lift back/up, open, pull back
He drew back the tent flap
close
lower
The pilot lowered the flaps as the aircraft came into land

ADJ

real

VERB + FLAP

get in/into
Far from getting into a flap over the controversy, the government has used the media attention to its advantage
put sb in/into
Having to cook for everyone at Christmas put his mother in a real flap

PREP

in a ~
I've never seen her in a flap; she's always so calm
~ over
a flap over nuclear issues