The most common and most likely answer to this crossword clue is the 6 letter word NIMBLE
N
I
M
B
L
E
More clues leading to the result NIMBLE
- Active amount of computer storage dropped in river
- Agile medic goes into river
- Agile doctor in centre of African river
- Swift upset leaders of Enlightenment by mercilessly lampooning new ideas
- Agile Northern Ireland doctor backed by the French
- Active doctor found in African river
- Agile doctor into line dancing
- Quick-moving river into which doctor falls
- Quick — storage unit’s engulfed by river
- Quick — doctor’s in river!
Buddy explains!

The straight part
We know that "Quick-moving" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case quick-moving = nimble.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does NIMBLE mean?
NIMBLE adjective- Adept at taking or grasping
- Quick and light in movement or action.
- Quick-witted and alert.