The most common and most likely answer to this crossword clue is the 8 letter word UPSTREAM
I've seen this crossword clue in The Daily Telegraph
U
P
S
T
R
E
A
M
More clues leading to the result UPSTREAM
- Raises squad to cross river nearer its source
- Leading group of students against the flow
- Puts rumpled sheets away from mouth
- Opposing current university rates, MP revolts
- Puts out paper opposing current tendencies
- Against the current, having periods of success before time, leaves
- Tamper with us struggling against the current
- Ahead, master swimming against the current
- At university, eccentric master is against the current trend
- Upset ram running amok against the current
Buddy explains!

The straight part
We know that "going against the flow" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case going against the flow = upstream.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 UPSTREAM mean?
UPSTREAM noun- Part of the river towards the upstream direction.
- (open-source software) The original developers or maintainers of software.
- To stream upward.
- (open-source software) To have (a software library, patch, etc.) accepted by the original developers of the related software, so that they maintain and distribute it.
- In a direction against the flow of a current or stream of fluid (typically water); upriver
- Involving exploration and pre-production rather than refining and selling
- In the direction from the client to the server
- (open-source software) maintained, owned or associated with the original developers of the given software; in contrast to a modified version downstream
- Towards the leading end (5′ end) of a DNA molecule
- Against the current.