The phrase "a tough task when" is correct and usable in written English.
It can be used to introduce a situation or condition that makes a task difficult.
Example: "It can be a tough task when you have limited resources to complete the project on time."
Alternatives: "a challenging job when" or "a difficult endeavor when".
Instead, he wanted them to think of it as no big deal, a tough task when dealing with a team not necessarily used to winning.
At the same time, A.I.G. must also hold onto skilled employees, a tough task when the firm is under restrictions that many of its competitors do not face.
"Parents are the front line of getting every child eating well but it's such a tough task when we're bombarded by less healthy food at every turn.
The survey also indicates that the BBC's new chairman, Michael Grade, faces a tough task when he takes up his position next month.
The Scotsman lasted less than a season at the helm of Manchester United before being sacked last April and took on a tough task when he agreed to take over a Sociedad side fighting relegation in November.
That means the Arsenal players will have Christmas Day off, but Wenger has warned his squad that they will face a tough task when they return to action at the Emirates Stadium two days later.
That's a particularly tough task when so many of those big ideas are premised on telling members of Congress, lobbyists, and other powers that be in Washington that the way they're doing things is morally wrong and coming to an end.
Lafayette Dublin had a clear but tough task when he took over the Rock Creek Christian Academy basketball team this season.
Keeping that cash flowing in a positive direction will depend on your facility's occupancy rate a tough task when a decent percentage of your customers have a tendency to die off.
Once described memorably as "as implausibly good-looking as a model from a Blue Stratos ad", Turner was even sexy in The Hobbit, a tough task indeed when one considers that the closest previous thing to sexy in big screen Tolkien fantasy was the odd bromantic interlude for Lord of the Rings' Sam and Frodo amid the murk and grime of Mordor.
Spectrum sensing is a tough task especially when signal-to-noise ratio (SNR) is low.
