May have "cleared" a threat by accident!

Hi, Everybody!

Apologies for my ignorance here--I'm relatively new to Sophos.  The software recently turned up a Threat, and I think I may have accidentally "cleared" it instead of cleaning it up!  If I did this, what are the consequences?  Will the threat turn up again in future scans?  Or have I in effect told Sophos to always ignore this threat?  If I've told it to always ignore the threat, is there anyway to undo this?

Thanks!

Spence