The most common and most likely answer to this crossword clue is the 7 letter word LEXICON
I've seen this crossword clue in The Times
L
E
X
I
C
O
N
More clues leading to the result LEXICON
- Classical law: I study a range of terminology
- Vocabulary of large person who used to be revered?
- Left graphic symbol on former reference work
- Roman law requires one to study vocabulary
- Left country without capital – new work either 22 could use🙂
- Law #1: study vocabulary
- Dictionary the French team study
- Former prisoner at length holds one reference
- Phrasebook with ‘wreath containing cross’? That’s got to mislead
- Reference image of Luthor?
Buddy explains!

The straight part
We know that "Vocabulary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vocabulary = lexicon.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 LEXICON mean?
LEXICON noun- The vocabulary of a language.
- A dictionary that includes or focuses on lexemes.
- A dictionary of Classical Greek, Hebrew, Latin, or Aramaic.
- The lexicology of a programming language. (Usually called lexical structure.)
- Any dictionary.
- The vocabulary used by or known to an individual. (Also called lexical knowledge)
- A vocabulary specific to a certain subject.