The most common and most likely answer to this crossword clue is the 10 letter word DOWNLOADED
I've seen this crossword clue in Financial Times
D
O
W
N
L
O
A
D
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D
Buddy explains!
The straight part
We know that "made a transfer online" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case made a transfer online = downloaded.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 DOWNLOADED mean?
DOWNLOADED verb- To transfer data from a remote computer (server) to a local computer, usually via a network.
- To upload; to copy a file from a local computer to a remote computer via a network.
- To transfer a file to or from removable media.
- To install software.