The most common and most likely answer to this crossword clue is the 5 plus 3 plus 13 letter word UNDER THE CIRCUMSTANCES
I've seen this crossword clue in The Times
U
N
D
E
R
T
H
E
C
I
R
C
U
M
S
T
A
N
C
E
S
Buddy explains!
The straight part
We know that "due to conditions" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case due to conditions = under the circumstances.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.