The most common and most likely answer to this crossword clue is the 7 letter word SCHEMER
I've seen this crossword clue in The Daily Telegraph
S
C
H
E
M
E
R
More clues leading to the result SCHEMER
- He meets the writer in SCR for Mastermind
- M Escher, perplexing creator of intricate designs?
- Devious type cheers possibly after pocketing money
- Boris finally the revolutionary? “Yours truly, right one to make a plan”
- Half of school rejected studying sacred books by this writer, one inventing plots
- Devious type in school set back engineers
- Plot developer
- He plans to no good purpose
- Cheer Ms. Messy, a shrewd planner
- He plots to have son, married, in good spirits
Buddy explains!

The straight part
We know that "one inventing plots" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one inventing plots = schemer.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 SCHEMER mean?
SCHEMER noun- One who plots or schemes, who formulates plans.
- One who is given to scheming.