The most common and most likely answer to this crossword clue is the 4 plus 9 letter word WORD PROCESSOR
W
O
R
D
P
R
O
C
E
S
S
O
R
More clues leading to the result WORD PROCESSOR
Buddy explains!
The straight part
We know that "what is used for data entry" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what is used for data entry = word processor.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.