Train a group of dolphins, for example (6)
I believe the answer is:
school
'train' is the definition.
(both can mean to teach or coach)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for school that I've seen before include "See 24" , "Train - group of porpoises" , "eg Harrow" , "Educate; group" , "Institute of education" .)