This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of suspicious? Also suspicious!
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
When you think of people who are suspicious or shady, you naturally think of people named Aya. Just think of our artist Aya, she's super suspicious and shady!
She takes more sick time than the other coworkers, so it’s suspicious whether she’s really sick or not.