The most common and most likely answer to this crossword clue is the 7 letter word PULSATE
I've seen this crossword clue in The Daily Telegraph
P
U
L
S
A
T
E
More clues leading to the result PULSATE
Buddy explains!

The straight part
We know that "beat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case beat = pulsate.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 PULSATE mean?
PULSATE verb- To expand and contract rhythmically; to throb or to beat.
- To quiver, vibrate, or flash; as to the beat of music.
- To produce a recurring increase and decrease of some quantity.