During commercial, seeing hospital department is accidental (11)
I believe the answer is:
inadvertent
'accidental' is the definition.
(I know that accidental can be written as inadvertent)
'during commercial seeing hospital department' is the wordplay.
'during' becomes 'in' (e.g. during February means in February).
'commercial' becomes 'advert' (I've seen this before).
'seeing hospital department' becomes 'ENT' (Ear, Nose and Throat department).
'in'+'advert'+'ent'='INADVERTENT'
'is' acts as a link.
(Other definitions for inadvertent that I've seen before include "Unthinking" , "Unintentional" , "Accidental" , "unguarded" , "without meaning" .)