The most common and most likely answer to this crossword clue is the 7 letter word TALLISH
T
A
L
L
I
S
H
More clues leading to the result TALLISH
- Composer reaching height? Rather unlikely
- Rather big feature of Stalin: holding back poor
- Hard-to-follow composer is fairly elevated
- This is fabricated — everything in it is somewhat implausible
- Quite elevated golf commentator contracted to occupy perimeter of twelfth
- Never short of such unbelievable stories?
Buddy explains!

The straight part
We know that "rather big" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rather big = tallish.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.