Reilly, 19, was handed his first-ever Blues start against Crystal Palace in mid-December and has since gone on to enjoy a total of 10 appearances this term, notching his maiden goal in a 1-1 draw at Huddersfield.
His exploits for Birmingham have been recognised with a first call-up to the Republic of Ireland Under-21s squad, playing 64 minutes in their 3-0 friendly win over Holland on Wednesday afternoon.
And Reilly admits his progress at St Andrew's is being aided by midfield veterans Clark, who starred for Newcastle, Sunderland and Fulham during his playing days, and McDermott, who pretty much won everything there is to win at Liverpool, including three European Cups and six First Division titles.
"It's fantastic," said. "The experience he (Clark) has is invaluable. You've obviously got Lee and you've got Terry as well. Terry played great in his position, he's got great experience, he knows a lot about the game.
"It's always great sponging off as much information as you can from both of them because they've got a lot to give."
Reilly is the latest in a number of Academy graduates to have thrived in Birmingham's first team over the last 18 months, along with the likes of Jordon Mutch, Nathan Redmond and Jack Butland.
"It's been great for the Academy, the Academy are really happy and they deserve everything as well because of how well they push the young lads, The coaching is top notch," Reilly added.