The most common and most likely answer to this crossword clue is the 8 letter word HEIGHTEN
I've seen this crossword clue in The Times
H
E
I
G
H
T
E
N
More clues leading to the result HEIGHTEN
- Figure blocking female in lift
- Build up layer, inserting cube
- Bring up figure in cooped up animal?
- Women-only screening of Cube and Up
- Female embracing crew in lift
- Add to our central figure in female
- Boost horse, 18, losing energy
- Number taken in by flighty female is to increase
- Female boxing crew to become more intense?
- Become more intense describing party crew disrupts
Buddy explains!

The straight part
We know that "Bring up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bring up = heighten.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 HEIGHTEN mean?
HEIGHTEN verb- To make high; to raise higher; to elevate.
- To advance, increase, augment, make larger, more intense, stronger etc.