Officer covered by transparent screen (7)
I believe the answer is:
shelter
'screen' is the definition.
(thesaurus)
'officer covered by transparent' is the wordplay.
'officer' becomes 'lt' (I've seen this in other clues).
'covered by' indicates putting letters inside.
'transparent' becomes 'sheer' ('sheer' can be a synonym of 'transparent').
'lt' going into 'sheer' is 'SHELTER'.
(Other definitions for shelter that I've seen before include "Place of refuge" , "Refuge, protection" , "Shield as from rain" , "Let hers go into shielded place" , "Refuge or protective cover" .)