The most common and most likely answer to this crossword clue is the 4 letter word BIKE
B
I
K
E
Buddy explains!

The straight part
We know that "two wheeler" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case two wheeler = bike.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 BIKE mean?
BIKE noun- A vehicle that has two wheels, one behind the other, a steering handle, and a saddle seat or seats and is usually propelled by the action of a rider’s feet upon pedals.
- A traveling block used on a cable in skidding logs.
- The best possible hand in lowball.
- A motorbike.
- (usually in compounds specifying a context) a slut; a promiscuous woman
- To ride a bike.
- To travel by bike.
- To transport by bicycle
- A motorcycle.
- A small and light motorcycle.
- A local woman who is sexually promiscuous.
- A hive of bees, or a nest of wasps, hornets, or ants.
- (by extension, collective) A crowd of people.