Think about me as shielding us (4)
I believe the answer is:
muse
'think' is the definition.
(I've seen this before)
'about me as shielding us' is the wordplay.
'about' shows that the letters should be reversed in order.
'me as' becomes 'em' (I am not sure about this - if you are sure you should believe this answer much more).
'shielding' means one lot of letters goes inside another.
'em' in reverse letter order is 'me'.
'me' going around 'us' is 'MUSE'.
Can you help me to learn more?
(Other definitions for muse that I've seen before include "Ponder or meditate" , "Goddess; rock group" , "The source of an artist's inspiration" , "Ponder in meditative way" , "Source of artistic inspiration" .)