The most common and most likely answer to this crossword clue is the 6 letter word BROODY
I've seen this crossword clue in The Guardian
B
R
O
O
D
Y
More clues leading to the result BROODY
Buddy explains!
The straight part
We know that "Deeply thoughtful/keen to raise issue" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case deeply thoughtful/keen to raise issue = broody.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 BROODY mean?
BROODY noun- A female bird in the condition to incubate eggs; a broody hen, duck, etc.
- Of birds: sitting persistently and protectively on a nest, in order to hatch eggs.
- Of any creature or person: showing an interest in raising young.