The phrase "a specific reason to" is correct and usable in written English.
It can be used when you want to indicate a particular justification or motive for an action or decision.
Example: "I need a specific reason to believe that this plan will succeed."
Alternatives: "a particular justification for" or "a clear motive to".
"Now, you need a specific reason to come in".
He gives interviews when he has a specific reason to do so.
"Religious in the sense that you don't need a specific reason to like Han Han".
Without a specific reason to ask for each person's identification, the court said, the demand is illegal.
I went today to the city of Misrata for a specific reason; to bear witness before Gaddafi's dead body.
Tom Lee, his domestic partner during Russell's last decade, remembers that when he did venture out to a club, he went for a specific reason: "To hear the sound of the records".
A government spokesman said: "Civil partnerships were created for a very specific reason – to give same-sex couples access to legal rights at a time when society was not ready to give them access to marriage.
If Mr. Coughlin likes to listen to the sea stories of pirates, it is for a very specific reason: to use them as confessions in court.
Yes, Mozilla is closing in on version 4.0 (I've been running the betas for some time now, and I'm a fan of the new Mac interface, while the Windows one looks sorta weird in Aero), and now Mac users have a rather specific reason to be excited: hardware acceleration.
According to Stahl, Trump told her that he continually "discredits" and "demeans" the press for a very specific reason: to sow uncertainty about the media so that "no one will believe" negative stories about him.
Unless there is some specific reason to pursue a person who has paid his proper debt to society, it is just not right to hassle him.
