The most common and most likely answer to this crossword clue is the 5 letter word LYMPH
I've seen this crossword clue in The Guardian
L
Y
M
P
H
More clues leading to the result LYMPH
- Fluid laboratory drained with speed
- Poorly MP hesitantly collecting bodily fluid
- Fluid fuel, say, ultimately adding speed
- Variable speed limit initially put on first part of circulatory system
- Extremely lazy method originally used to measure alkaline level of fluid
- Not fine, dash off with measure of speed to get fluid
Buddy explains!

The straight part
We know that "bodily fluid" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bodily fluid = lymph.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 LYMPH mean?
LYMPH noun- (poetical) Pure water.
- A colourless, watery bodily fluid, carried by the lymphatic system, that consists mainly of white blood cells.
- Discharge from a sore, inflammation etc.