ACE UP ONE'S SLEEVE (OR N. AMER. IN THE HOLE)
Meaning of ACE UP ONE'S SLEEVE (OR N. AMER. IN THE HOLE) in English
ace up one's sleeve ( or N. Amer. in the hole)
something effective kept in reserve.
→ ace
Concise Oxford English vocab.
Сжатый оксфордский словарь английского языка.
2004