The most common and most likely answer to this crossword clue is the 5 letter word HYPER
I've seen this crossword clue in The Times
H
Y
P
E
R
More clues leading to the result HYPER
- Very energetic and touchy person fraying at the edges
- Overexcited person pushing a product very hard?
- Frantic person doing marketing?
- Pumped up dinghy, perhaps, that’s shrunk
- Overexcited from honeymoon: young princess enjoyed romance, initially
- Received by monarchy, perhaps overly excited?
- Extremely happy salesman turned up, unusually energetic
- Over-excited pushy person must contain this
- Over-excited and somewhat pushy person
- That woman, employing leaders in youth programme, becomes very excited
Buddy explains!

The straight part
We know that "Overexcited" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case overexcited = hyper.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 HYPER mean?
HYPER noun- Hyperextension exercise
- Hyperspace
- Hyperactive
- Energetic; overly diligent
- A wrestler who uses the hipe technique.