This effect targets the Spell Card in your GY.
When you Synchro Summon a Spellcaster-Type monster with "Urgent Tuning" that was activated as Chain Link 2 or higher using "Magicat" as a Synchro Material Monster, you can activate the effect to return a Spell Card in a new Chain after the first one resolves.
If "DNA Surgery" is changing monsters into Spellcasters and you use this card for a Synchro Summon, you can activate its effect.