The most common and most likely answer to this crossword clue is the 6 letter word DINGUS
D
I
N
G
U
S
Buddy explains!

The straight part
We know that "doodad" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case doodad = dingus.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 DINGUS mean?
DINGUS noun- A gadget, device, or object whose name is either unknown, forgotten, or omitted for the purpose of humor.
- A fool or incompetent person.
- Penis