Of course “足球诊所” doesn't make sense. Is “足球培训班” accurate? But I feel like soccer clinic is like a one time thing, while 足球培训班 implies there are multiple classes.
1Maybe "足技中心" fitting the purposes - skill training, technics improvment, knowledge, and strategy consultation. The full name could be "足球技術訓練中心" or "足球技術交流中心".– r13May 22, 2021 at 20:03
1For one-time tutoring class, you can say 讲习课 / 培训课. Alternatively, you can say soccer workshop, 足球工作坊 (fáng).– BósàiMay 22, 2021 at 23:51
1Clinic means "a group session offering counsel or instruction in a particular field or activity", so I prefer "训练营".– T-PioneerMay 23, 2021 at 3:24
When I was small, I went to 足球培训班, so this must make sense.
足球集训班 or 足球特训班, 集训 or 特训 is different from 训练班, though people won't know the schedule via the name.