Series opener pitchers, often (4)

I believe the answer is:

aces

(Other definitions for aces that I've seen before include "Honours" , "Two will make deuce" , "Expert fliers" , "passes with flying colours in US" , "Unreturnable services" .)

I've seen this clue in The Wall Street Journal.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.