The most common and most likely answer to this crossword clue is the 3 letter word ISP
I've seen this crossword clue in Independent
I
S
P
Buddy explains!
The straight part
We know that "What’s needed to surf" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what’s needed to surf = isp.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 ISP mean?
ISP noun- Any species known only from trace fossils, such as footprints, coprolites or nests.