Power to recall (6)
I believe the answer is:
memory
'power to recall' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for memory that I've seen before include "Power of retaining and recalling past experience" , "Mental retention" , "Computer storage" , "The ability to store things in mind, and to recall (6)" , "Recollection" .)