Witness working with handsome type (8)
I believe the answer is:
onlooker
'witness' is the definition.
(I know that onlooker is a type of witness)
'working with handsome type' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'with handsome type' becomes 'looker' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'on'+'looker'='ONLOOKER'
Can you help me to learn more?
(Other definitions for onlooker that I've seen before include "He stands and watches" , "One observes" , "He's not involved - just observing" , "Spectator" , "Bystander" .)