The phrase "a while to earn" is correct and usable in written English.
It can be used when discussing the time it takes to achieve or acquire something, often in the context of money or respect.
Example: "It took me a while to earn the trust of my colleagues after the incident."
Alternatives: "some time to gain" or "a period to achieve".
Getting the pinfeathers out is murder, and cheap Canadian imports made it hard for a while to earn a profit.
Puppet master It used to be difficult to give Martin Whitmarsh the respect a team principal deserved – thanks to his aerospace background – and he took a while to earn his racing stripes.
It takes a while to earn back that $6,000 at the gas pump.
Especially when it takes a while to earn.
(It's possible, of course, that his recalcitrance is just a put-on act that he's got to perform for a while to earn, or keep, the respect of his fellow House Republicans.
It takes a while to earn the affection of a child -- and some of the things you have to do to earn it (or to play with them), well, they take patience too.
Leinster took a while to get going but eventually earned a bonus-point win to add to Edinburgh's recent misery.
It takes some graduates a while to reach their full earning potential.
With their counterparts from South Korea, the women have established a familial bond while pushing to earn a reputation as a strong team, not just as one gifted a berth into their first Olympic appearance as the host nation.
Meanwhile, down the road on Hampstead Heath a couple of hours later, dozens of athletes are being roared on as they charge through a beer tent while trying to earn a spot in the British team for the Olympics.
But Ted still needs a close supervisor to enable him to get out and into the community, a role Sarah can't fill while trying to earn a living.
