The most common and most likely answer to this crossword clue is the 4 letter word MWAH
M
W
A
H
More clues leading to the result MWAH
Buddy explains!

The straight part
We know that "Suggestion of kiss" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case suggestion of kiss = mwah.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 MWAH mean?
MWAH noun- The hallmark sound of a fretless bass guitar played with a certain technique, where treble frequencies increase gradually after the attack.
- The sound of a kiss to indicate blowing a kiss to someone.