to insert; to put between; to tuck (into)
名刺をノートに挟み込んだ。
I tucked the business card into my notebook.
誰かが本にチラシを挟み込んでいる。
Someone has inserted a flyer into the book.
整備士は隙間調整のために薄板を挟み込む。
The mechanic inserts a thin shim to adjust the gap.