The most common and most likely answer to this crossword clue is the 7 letter word SOULFUL
S
O
U
L
F
U
L
More clues leading to the result SOULFUL
Buddy explains!

The straight part
We know that "deeply expressive" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case deeply expressive = soulful.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 SOULFUL mean?
SOULFUL adjective- Full of emotion and vigor.
- Full of soul.
- Enough to fill one's soul.