The term 'uptake quick on the' can be completed with the crossword solutions of ALERT, SMART, ASTUTE, and APT. ALERT is an adjective meaning to be watchful or attentive, SMART is an adjective meaning to be intelligent or clever, ASTUTE is an adjective meaning to be shrewd or perceptive, and APT is an adjective meaning to be suitable or appropriate. Together, these words suggest that someone is able to quickly understand and respond to a situation in an intelligent and suitable manner.