Stress I had included crash (8)
I believe the answer is:
accident
'crash' is the definition.
(thesaurus)
'stress i had included' is the wordplay.
'stress' becomes 'accent' (accent can mean to emphasise or stress).
'i had' becomes 'i'd' (I'd).
'included' means one lot of letters goes inside another.
'accent' placed around 'id' is 'ACCIDENT'.
(Other definitions for accident that I've seen before include "Pile-up" , "Calamity" , "Contretemps" , "Chance event with no apparent cause" , "Chance misfortune or injury" .)