Suffixes are word parts added to the end of a word to change its meaning or grammatical function.
"Smirk" is a complete word on its own, and it doesn't typically combine with suffixes to create new words.
However, you could use related words with suffixes:
* Smirkingly (adverb)
* Smirker (noun)
* Smirky (adjective)
These words use suffixes to modify the meaning of "smirk" to describe the action, the person, or the quality of the smirk.