Full Idea
The 'induction clause' says that whenever one constructs more complex formulas out of formulas that have the property P, the resulting formulas will also have that property.
Gist of Idea
The 'induction clause' says complex formulas retain the properties of their basic formulas
Source
Graham Priest (Intro to Non-Classical Logic (1st ed) [2001], 0.2)
Book Reference
Priest,Graham: 'Introduction to Non-Classical Logic' [CUP 2001], p.-5