The most common and most likely answer to this crossword clue is the 7 letter word WHATSIT
I've seen this crossword clue in The Daily Telegraph
W
H
A
T
S
I
T
More clues leading to the result WHATSIT
- Funny character securing lids, I forget the name
- Something unknown twit has arranged
- Gadget comedian keeps headgear in
- Humour about bowler’s thingy?
- Nameless person seen in straw hat, sitting
- Something or other employing old serving women in religious festival
- Cooking with fat’s not fine for thingamy
- Joker holding fedoras, say! Name escapes me?
- Thingummy with a hollow shaft, broken
- So-and-so, with task almost entirely messed up
Buddy explains!

The straight part
We know that "thingy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case thingy = whatsit.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 WHATSIT mean?
WHATSIT noun- A thing (used in a vague way to refer to something whose name one cannot recall, or that one is embarrassed to say)