The most common and most likely answer to this crossword clue is the 7 letter word INKBLOT
I've seen this crossword clue in The Guardian
I
N
K
B
L
O
T
More clues leading to the result INKBLOT
- Paper smear exposing personality
- Across back of book, broken nib’s load producing this?
- Mark part of test
- Blink perplexedly at books to find writing error
- Stationery item with Mark's needed for the psychological test pattern
- Close to Sgt Bilko, worried about new part of psychology test
- It’s a test – failing to blink
Buddy explains!

The straight part
We know that "Paper smear" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case paper smear = inkblot.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 INKBLOT mean?
INKBLOT noun- A blot of ink
- A dark, shapeless object
- One of the pictures used as stimuli in the Rorschach inkblot test