The most common and most likely answer to this crossword clue is the 10 letter word PERSONALLY
I've seen this crossword clue in The Times
P
E
R
S
O
N
A
L
L
Y
More clues leading to the result PERSONALLY
- For a joke, holding on to me
- I believe backsliding saleswoman and boyfriend must be split up!
- Boy participating in gym to improve as an individual
- Loner plays foolishly, in my opinion
- Privately friendly, hugging Queen and heir
- Only pearls flawed, as far as one is concerned
- In the flesh, ‘tight’ describes Queen’s playing
- In my opinion, after gym, boy must go into assembly
- Without resistance, Noel’s play’s rewritten for my part
- For myself and for each member of the family, a friend
Buddy explains!

The straight part
We know that "I believe" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i believe = personally.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 PERSONALLY mean?
PERSONALLY adverb- In a personal manner.
- In person.
- Concerning oneself.
- As a person.