The most common and most likely answer to this crossword clue is the 7 letter word HAWKING
I've seen this crossword clue in Financial Times
H
A
W
K
I
N
G
Buddy explains!
The straight part
We know that "Physicist/pitching on the street" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case physicist/pitching on the street = hawking.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 HAWKING mean?
HAWKING verb- To hunt with a hawk.
- To make an attack while on the wing; to soar and strike like a hawk.
- To sell; to offer for sale by outcry in the street; to carry (merchandise) about from place to place for sale; to peddle.
- To cough up something from one's throat.
- To try to cough up something from one's throat; to clear the throat loudly.
- Action of the verb to hawk.