It would still be foolish if son were involved (5)

I believe the answer is:

inane

I'm a little stuck... Click here to teach me more about this clue!

'involved' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for inane that I've seen before include "Stupid and silly" , "Silly, witless" , "Unintelligent" , "Really stupid" , "Lacking sense, silly" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.