leading light 
noun
A person who is prominent or influential in a particular field or organization: Lesley is a leading light in a local netball team...
- He is probably the leading light in the field of Australian improvised music.
- Everyone would have to admit that Graham proved himself a leading light on the field of play.
- In the last 15 years Scotland has been a leading light in the field of public art and public sculpture.
- over-dance
- over-daring
- overdate
- overdated
- overdating
- overday
- overdeal
- overdear
- overdeck
- overdecorated
- overdeepen
- overdeepened
- overdeepening
- overdelicacy
- overdelicate
- over-delicately
- over-deliver
- over-density
- overdependence
- overdependent
- overdesign
- over-desire
- over-desirous
- overdetailed
- overdetermination