The most common and most likely answer to this crossword clue is the 8 letter word ELBOWING
I've seen this crossword clue in The Daily Telegraph
E
L
B
O
W
I
N
G
Buddy explains!

The straight part
We know that "Pushing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pushing = elbowing.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 ELBOWING mean?
ELBOWING verb- To push with the elbow.
- (by extension) To nudge, jostle or push.
- A nudge or jostle with the elbow.