The phrase "ambition to improve" is correct and can be used in written English.
You can use it when you want to express that someone has a strong desire or ambition to make something better. For example, "She has an ambition to improve her academic performance and reach the highest level of education possible."
Going back to Bam, Mountford was encouraged by people's desire for change and their ambition to improve their lives.
We persisted because our ambition to improve our customers' financial lives means that we are always falling short.
"What we need now is to move forward with a shared ambition to improve these aspects of the offer for the audience in Scotland.
Mr. Boehner explains his rise from a childhood with little money to the Congressional leadership by recalling his ambition to improve his life.
You want to find that balance between self-confidence and arrogance, and an ability to enjoy the moment versus an ambition to improve.
A European diplomat based here said the president "had, and for all I know still has, a genuine ambition to improve the conditions in this country".
The idea evidently encouraged Portland cluster members, whose ambitions to improve American education belie their small corporate size.
The one promising thing about Kim Jong Un is that he harbors ambitions to improve North Korea's economy, and his domestic policies have already generated modest growth.
Economic stability underpins not just Labour's ambitions to improve the public services through a sustained programme of higher spending but also public confidence in Labour's ability to manage the economy.So far, the government has fulfilled its promise.
Chris Froome's ambitions to improve on the bronze medal he won in the men's time trial at London 2012 were thwarted when he had to settle for another bronze behind Fabian Cancellara and Tom Dumoulin.
