I engaged in virtual reality leading to American computer problem (5)
I believe the answer is:
virus
'computer problem' is the definition.
(I've seen this before)
'i engaged in virtual reality leading to american' is the wordplay.
'engaged in' is an insertion indicator.
'leading' indicates taking the first letters.
'to american' becomes 'us'.
The initial letters of 'virtual reality' is 'vr'.
'i' put within 'vr' is 'vir'.
'vir'+'us'='VIRUS'
(Other definitions for virus that I've seen before include "Disease carrier or computer bug" , "Microscopic infectant" , "Cause of computer failure?" , "Submicroscopic organism, cause of disease" , "Bodily or computer infection" .)