The phrase "and only purpose" is correct and usable in written English.
It can be used to emphasize that something has a singular or exclusive aim or intention.
Example: "The mission of this organization is clear: to serve the community and only purpose."
Alternatives: "sole purpose" or "exclusive aim".
This, however, expresses no purpose to exempt judicial authority from constitutional limitations, since its great and only purpose is to secure judicial authority from obstruction in the performance of its duties to the end that means appropriate for the preservation and enforcement of the Constitution may be secured.
And only purpose with accomplishment can drive lasting satisfaction.
But Manning's sole and only purpose was to get out the truth.
Romney and the Bain crew couldn't have cared less whether their actions created jobs, eliminated jobs, or destroyed entire communities so long as they served their one and only purpose: making themselves and their colleagues very, very rich.
You will literally witness the sleeping light from within their soul rise to fulfill their one-and-only purpose here on this earth -- to champion the energy of true love and its promise of global enlightenment.
The seaside village of Anderby Creek, Lincolnshire, is home to the UK's first – and only – purpose-built cloud-viewing platform.
"The female members are treated like communal property, and their only purpose is sex and holding weapons and drugs," Officer Montero said.
"The tone would be light and farcical throughout," he says, "and my only purpose was to keep myself entertained".
They are in a wave pattern and their only purpose seems to have been to move on the homeless man and his dog".
Friends are not to be made, but won, and the only purpose of making friends is to get them to do what you want.
She described the royal as a "shop-window mannequin", "gloss-varnished" with no personality and whose only purpose was to breed.
