The most common and most likely answer to this crossword clue is the 4 letter word BEAN
I've seen this crossword clue in The Times
B
E
A
N
More clues leading to the result BEAN
Buddy explains!

The straight part
We know that "Pulse" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pulse = bean.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 BEAN mean?
BEAN noun- A reusable software component written in Java.
- Any plant of several genera of the taxonomic family Fabaceae that produces large edible seeds or edible seedpods.
- The large edible seed of such a plant (for example, a broad bean, navy bean or garbanzo bean).
- The edible seedpod of such a plant.
- (by extension) The bean-like seed of certain other plants, such a a vanilla bean or (especially) a coffee bean.
- (by extension) An object resembling a pea or bean in shape, often made from plastic or styrofoam and used in large numbers as packing material or as stuffing for beanbags and similar items.
- The head or brain.
- The clitoris.
- A person.
- A guinea coin.
- (usually in the negative) Money.
- To hit deliberately with a projectile, especially in the head.