How to write a regular expression - searching for a value between commas?

Question

Regular Expressions

$subject = "Website development,Website development,Website design,Website promotion,Website promotion,SEO website promotion,Website support";
$searchstring="motion"
$pattern = "/[,][a-zA-Za-zA-Z]*".$searchstring."[a-zA-Za-zA-Z]*[,]/";
preg_match($pattern, $subject, $matches, PREG_OFFSET_CAPTURE);
How to write an expression to return "Website promotion"?

Answer 1

https://regex101.com/r/aM5oU3/9