Ace

the smallest whole number or a numeral representing this number

one of four playing cards in a deck having a single pip on its face

someone who is dazzlingly skilled in any field

proteolytic enzyme that converts angiotensin I into angiotensin II

a major strategic headquarters of NATO

a serve that the receiver is unable to reach

succeed at easily

score an ace against

play (a hole) in one stroke

serve an ace against (someone)

of the highest quality