"difficult way" is correct and usable in written English.
You can use it when referring to a complicated or challenging path or method. For example, "He took the difficult way to confront his fears."
"It is a difficult way to learn the business".
Britain faces this divide in a particularly difficult way.
Making smart money decisions is an incredibly difficult way to behave.
The most difficult way of decorating iron is to carve it.
The feature was spotted by Android Police, who detailed the difficult way to activate it.
"It's a difficult way, but it's the only choice we have," Mr. Mirzaie said.
"It's changed the whole psychology of the country in a very difficult way," he says.
"I feel like everything I've done, I've taken the difficult way," she said.
Running a pub in this environment is a difficult way to make a living but I believe it is important".
"When it's good it's very good, but it's a difficult way to make a living," he said.
It seemed to me a much more difficult way to write a novel, but also it was quite liberating.
