Took a risk, as about to interrupt father (5)
I believe the answer is:
dared
'took a risk' is the definition.
(I've seen this before)
'about to interrupt father' is the wordplay.
'about' becomes 're' (regarding**).
'to interrupt' indicates putting letters inside.
'father' becomes 'dad' (dad is a kind of father).
're' inserted inside 'dad' is 'DARED'.
'as' is the link.
(Other definitions for dared that I've seen before include "was bold enough" , "Challenged - was audacious" , "Took a risk" , "Was brave enough" , "Acted with courage - or dread?" .)