The most common and most likely answer to this crossword clue is the 6 letter word UPTAKE
I've seen this crossword clue in The Daily Telegraph
U
P
T
A
K
E
Buddy explains!

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 UPTAKE mean?
UPTAKE noun- Understanding; comprehension.
- Absorption, especially of food or nutrient by an organism.
- The act of lifting or taking up.
- A chimney.
- The upcast pipe from the smokebox of a steam boiler towards the chimney.
- To take up, to lift.
- To absorb, as food or a drug by an organism.
- To accept and begin to use, as a new practice.