One complete fabrication about son's hero-worship (7)
I believe the answer is:
idolise
'hero-worship' is the definition.
('hero-worship'->'idolize' is in my internal thesaurus and 'ize'->'ise')
'one complete fabrication about son's' is the wordplay.
'one' becomes 'i' (Roman numeral).
'complete' becomes 'do' (doing is a kind of completing**).
'fabrication' becomes 'lie' (I've seen this before).
'about' indicates putting letters inside.
'lie' enclosing 's' is 'lise'.
'i'+'do'+'lise'='IDOLISE'
(Other definitions for idolise that I've seen before include "Worship and adore" , "Hero-worship, revere" , "Revere, love greatly" , "Worship (S, not Z)" , "Pay excessive attention to" .)