The most common and most likely answer to this crossword clue is the 9 letter word INPUTTING
I've seen this crossword clue in The Daily Telegraph
I
N
P
U
T
T
I
N
G
More clues leading to the result INPUTTING
Buddy explains!

The straight part
We know that "Entering" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case entering = inputting.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 INPUTTING mean?
INPUTTING verb- To put in; put on.
- To enter data.
- To accept data that is entered.