The most common and most likely answer to this crossword clue is the 4 letter word TERM
T
E
R
M
More clues leading to the result TERM
- Hesitation to get into meditation when lectures should be attended?
- Measure of heat needed in the absence of hot period
- Eg, Trinity’s empty when 3rd is close to poor
- Hilary's one / expression
- Session spanning winter months
- Some better material seen in part of school year
- Word: also sentence
- Name: Hilary, for example
- Hilary’s one expression
- Some semester mainly
Buddy explains!

The straight part
We know that "Label/spell behind bars" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case label/spell behind bars = term.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 TERM mean?
TERM noun- That which limits the extent of anything; limit, extremity, bound, boundary.
- A chronological limitation or restriction.
- Any of the binding conditions or promises in a legal contract.
- A point, line, or superficies that limits.
- A word or phrase, especially one from a specialised area of knowledge.
- Relations among people.
- Part of a year, especially one of the three parts of an academic year.
- Duration of a set length; period in office of fixed length.
- With respect to a pregnancy, the period during which birth usually happens (approximately 40 weeks from conception).
- (of a patent) The maximum period during which the patent can be maintained into force.
- A menstrual period.
- Any value (variable or constant) or expression separated from another term by a space or an appropriate character, in an overall expression or table.
- The subject or the predicate of a proposition; one of the three component parts of a syllogism, each one of which is used twice.
- An essential dignity in which unequal segments of every astrological sign have internal rulerships which affect the power and integrity of each planet in a natal chart.
- A statue of the upper body, sometimes without the arms, ending in a pillar or pedestal.
- A piece of carved work placed under each end of the taffrail.
- To phrase a certain way; to name or call.
- Born or delivered at term.
- A computer program that emulates a physical terminal.
- One whose employment has been terminated
- To terminate one's employment