The most common and most likely answer to this crossword clue is the 5 letter word HEAVY
I've seen this crossword clue in The Guardian
H
E
A
V
Y
More clues leading to the result HEAVY
- Rough, unknown labourer, thrown outside
- Surprised cry about a very strong form of Scottish beer
- Serious actor playing villainous roles
- Overweight actor playing the villain?
- Bouncer not filled with air then?
- Substantial job as hired muscle?
- Leaders deserting the navy — that’s hard to bear
- Gangster's bodyguard is not light
Buddy explains!

The straight part
We know that "Bouncer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bouncer = heavy.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 HEAVY mean?
HEAVY noun- A villain or bad guy; the one responsible for evil or aggressive acts.
- A doorman, bouncer or bodyguard.
- A large multi-engined aircraft. (The term heavy normally follows the call-sign when used by air traffic controllers.)
- (often with "up") To make heavier.
- To sadden.
- To use power and/or wealth to exert influence on, e.g., governments or corporations; to pressure.
- (of a physical object) Having great weight.
- (of a topic) Serious, somber.
- Not easy to bear; burdensome; oppressive.
- Good.
- (late 1960s, 1970s) Profound.
- (of a rate of flow) High, great.
- Armed.
- Louder, more distorted.
- (of weather) Hot and humid.
- (of a person) Doing the specified activity more intensely than most other people.
- (of food) High in fat or protein; difficult to digest.
- Of great force, power, or intensity; deep or intense.
- Laden to a great extent.
- Laden with that which is weighty; encumbered; burdened; bowed down, either with an actual burden, or with grief, pain, disappointment, etc.
- Slow; sluggish; inactive; or lifeless, dull, inanimate, stupid.
- Impeding motion; cloggy; clayey.
- Not raised or leavened.
- (of wines or spirits) Having much body or strength.
- With child; pregnant.
- Containing one or more isotopes that are heavier than the normal one
- (petroleum) with high viscosity
- In a heavy manner; weightily; heavily; gravely.
- To a great degree; greatly.
- Very
- Having the heaves.