Hide classified file at base (7)
I believe the answer is:
secrete
'hide' is the definition.
(I've seen this before)
'classified file at base' is the wordplay.
I cannot quite understand how this works, but
'classified' could be 'secret' (similar in meaning) and 'secret' is located in the answer.
'base' could be 'e' (Euler's number - base of natural logarithms) and 'e' is located in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for secrete that I've seen before include "squirrel" , "Hide or conceal an object" , "Form substance for use within body, as liver does bile" , "Place out of sight, hide" , "Hide; as gland does" .)