The most common and most likely answer to this crossword clue is the 8 letter word BARNACLE
I've seen this crossword clue in The Sunday Telegraph
B
A
R
N
A
C
L
E
More clues leading to the result BARNACLE
- Crustacean in pub clean when cooked
- Hanger-on, one locking up pound by farm building
- Good shot behind farm building bags large kind of goose
- On the coast it's hard to remove salt in mere
- Hanger-on in farm building, one left inside
- Farm building expert brings in large inconvenience to Hull
- One firmly sticks rod on clean ground
- Creature in farm building spinning lace
- Hanger-on may be stalked
- Hanger-on finding resistance in balance disturbed
Buddy explains!

The straight part
We know that "crustacean" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case crustacean = barnacle.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 BARNACLE mean?
BARNACLE noun- A marine crustacean of the subclass Cirripedia that attaches itself to submerged surfaces such as tidal rocks or the bottoms of ships.
- The barnacle goose.
- In electrical engineering, a change made to a product on the manufacturing floor that was not part of the original product design.
- On printed circuit boards, a change such as soldering a wire in order to connect two points, or addition such as an added resistor or capacitor, subassembly or daughterboard.
- A deprecated or obsolete file, image or other artifact that remains with a project even though it is no longer needed.
- (in the plural) An instrument like a pair of pincers, to fix on the nose of a vicious horse while shoeing so as to make it more tractable.
- (in the plural) A pair of spectacles.
- A good job, or snack easily obtained.
- A worldly sailor.
- To connect with or attach.
- To press close against something.