An old pro is someone who has a lot of experience in a particular field. A STAGER (6 letters) is someone who sets up the stage for a performance, a GURU (4 letters) is an EXPERT in a certain field, a lifer (5 letters) is someone who has been in a particular job or organization for a long time, an EXPERT (6 letters) is someone who has a high level of knowledge or skill in a particular area, an ACE (3 letters) is someone who is very skilled at something, a VETERAN (7 letters) is someone who has had a lot of experience in a particular field, a VET (3 letters) is someone who has served in the military, and a grizzled VETERAN (15 letters) is someone who has a lot of experience in a particular field and is often seen as wise and respected.