Computers etc starting to cause headaches and irritation (4)
I believe the answer is:
itch
'irritation' is the definition.
(I've seen this in other clues)
'computers etc starting to cause headaches' is the wordplay.
'computers etc' becomes 'IT' (short for Information Technology).
'starting to' says to take the initial letters.
The first letters of 'cause headaches' is 'ch'.
'it'+'ch'='ITCH'
'and' acts as a link.
(Other definitions for itch that I've seen before include "Nagging wish" , "burn" , "are dying" , "following seven years in union?" , "Skin irritation" .)