The most common and most likely answer to this crossword clue is the 3 plus 4 plus 8 letter word THE PLOT THICKENS
I've seen this crossword clue in The Sunday Telegraph
T
H
E
P
L
O
T
T
H
I
C
K
E
N
S
More clues leading to the result THE PLOT THICKENS
- Picks tenth hotel on tour: it gets complicated
- Complications ensue as more points are added to graph
- Struggling to help sect, think things are getting complicated
- Picks tenth hotel out as circumstances are becoming more and more complicated
- Ground becoming deeper? That’s more intriguing
- Kitchen help and tots fall out: things are becoming complicated
Buddy explains!
The straight part
We know that "That’s more intriguing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that’s more intriguing = the plot thickens.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.