The most common and most likely answer to this crossword clue is the 4 plus 4 letter word BARN DOOR
I've seen this crossword clue in The Times
B
A
R
N
D
O
O
R
More clues leading to the result BARN DOOR
- An easy target, but donor’s unsettled
- New onboard motor's last thing you should hit!
- You can’t miss it on board at sea before year’s end
- You could hardly miss it on the farm!
- Easy target making one flap
- One shouldn’t miss this store opening
- Airline service: con or easy target?
- It’s hard to miss terribly tedious person, per Spooner
Buddy explains!
The straight part
We know that "thing you should hit!" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case thing you should hit! = barn door.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.