Started to carry large screen (6)
I believe the answer is:
shield
'screen' is the definition.
('shield' can be a synonym of 'screen')
'started to carry large' is the wordplay.
'started' becomes 'shied' (shying is a kind of starting).
'to carry' indicates putting letters inside.
'large' becomes 'l'.
'shied' placed around 'l' is 'SHIELD'.
(Other definitions for shield that I've seen before include "Protective structure or device" , "Protective covering" , "Protective cover" , "Piece of plated armour" , "where you may find your bearings" .)