Think it will give you a mirror image (7)
I believe the answer is:
reflect
'think' is the definition.
(reflecting is a kind of thinking)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for reflect that I've seen before include "chew the cud" , "Think - send back" , "Display" , "'Ponder, chew over (7)'" , "Contemplate like mirror" .)