The most common and most likely answer to this crossword clue is the 9 letter word DISCHARGE
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More clues leading to the result DISCHARGE
Buddy explains!

The straight part
We know that "Release" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case release = discharge.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 DISCHARGE mean?
DISCHARGE noun- Pus or exudate (other than blood) from a wound or orifice, usually due to infection or pathology.
- The act of accomplishing (an obligation) or repaying a debt etc.; performance.
- The act of expelling or letting go.
- The act of firing a projectile, especially from a firearm.
- The process of unloading something.
- The process of flowing out.
- The act of releasing an accumulated charge.
- The act of releasing an inpatient from hospital.
- The act of releasing a member of the armed forces from service.
- The volume of water transported by a river in a certain amount of time, usually in units of m3/s (cubic meters per second).
- To accomplish or complete, as an obligation.
- To free of a debt, claim, obligation, responsibility, accusation, etc.; to absolve; to acquit; to forgive; to clear.
- To send away (a creditor) satisfied by payment; to pay one's debt or obligation to.
- To set aside; to annul; to dismiss.
- To expel or let go.
- To let fly, as a missile; to shoot.
- To release (an accumulated charge).
- To relieve of an office or employment; to send away from service; to dismiss.
- To release legally from confinement; to set at liberty.
- To operate (any weapon that fires a projectile, such as a shotgun or sling).
- To release (an auxiliary assumption) from the list of assumptions used in arguments, and return to the main argument.
- To unload a ship or another means of transport.
- To put forth, or remove, as a charge or burden; to take out, as that with which anything is loaded or filled.
- To give forth; to emit or send out.
- To let fly; to give expression to; to utter.
- To bleach out or to remove or efface, as by a chemical process.
- To prohibit; to forbid.