Masterclass

n.capable, thoughtfulprofessional

What it means

An expert lesson or an outstanding demonstration from which others can learn.

Reach for it when praising instruction or performance that reveals transferable craft, not excellence with no teaching value

The engineer's repair was a masterclass in diagnosing the simplest cause first.

playful
clinic
sports or performance commentary praises a dominant technical display
not when Because clinic also names a medical facility, context must make the sports metaphor plain.
everyday
expert lesson
high-level teaching is the literal event
not when Expert lesson says who teaches but not whether the result is exemplary.
warm
model lesson
instruction is designed for other teachers to adapt
not when Model lesson concerns pedagogy and not a brilliant real-world performance.
professional
demonstration
a technique is shown in action
not when Demonstration can be routine and may offer little explanation.
professional
tutorial
step-by-step instruction helps someone perform a task
not when A tutorial may be elementary; recognized mastery is optional.
formal
exemplar
one case provides a model worth studying
not when An exemplar need not teach or be presented by an expert.
literary
tour de force
exceptional skill makes the achievement impressive
not when A tour de force can be dazzling without revealing how others might learn from it.

masterclass in design
The folding bridge is a masterclass in design for repair.
give a masterclass
The veteran potter will give a masterclass in shaping large vessels.
attend a masterclass
Young conductors attended a masterclass on rehearsing new music.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.