Herald opening of picture with touching on-screen presence (9)
I believe the answer is:
precursor
'herald' is the definition.
('precursor' can be a synonym of 'herald')
'opening of picture with touching on-screen presence' is the wordplay.
'opening of' indicates taking the first letters.
'with' says to put letters next to each other.
'touching' becomes 're' (I've seen this in other clues).
'on-screen presence' becomes 'cursor' (present on a computer screen).
The initial letter of 'picture' is 'p'.
'p'+'re'+'cursor'='PRECURSOR'
(Other definitions for precursor that I've seen before include "I was here first" , "Something going in advance of another" , "Forerunner, predecessor" , "Man coming before me" , "Herald" .)