PHP Advanced field

Identify item in a string, remove all non alphanumeric items including /, -, + , so I may be able to place into a short code via php . For instance I want too remove Winter Garden from here. [login to view URL] And be able to insert it into something as simple as [idx-listings city="Winter Garden" statuses="1,2" orderby="DateAdded" orderdir="DESC" count="10" showlargerphotos="true" map="true"] Both my widgets and pages are able to have php in the wordpress theme. Just need to discover the coding for the path.