"clamber out" is a perfectly acceptable phrase in written English.
It means to climb out, usually with difficulty or effort. For example, "I had to clamber out of the broken window to escape the burning building."
As we clamber out quickly, we're as pink as beetroots.
(Rats aren't fond of being in the water, and the platform allowed them to clamber out).
The tide is low, so we clamber out along the sharp-edged reef.
"You did well," says Stiller, as we clamber out and carry the boat in to dry.
Some people dared to clamber out on to slippery rooftops to survey the scene below.
The hole has netting hanging from it, so they can't clamber out again.
The police allowed them to clamber out as the crowd swelled with supporters.
After an exhilarating leap into the deep turquoise water, I clamber out up a rickety bamboo ladder.
Day 40: The young are able to climb well, at which time they may leave the nest and clamber out along a tree branch.
As the two vehicles come to a halt, a bunch of actors clamber out, watched closely by director Mike Pearson.
Perhaps in time he will clamber out to write a whole novel with the range and spellbinding allure of those first 16 pages.
