Tiny bit powerless - exterior is impossible to find (11)
I believe the answer is:
untraceable
'impossible to find' is the definition.
I can't tell whether this defines the answer.
'tiny bit powerless exterior' is the wordplay.
'tiny bit' becomes 'trace' (I've seen this in another clue).
'powerless' becomes 'unable' (similar in meaning).
'exterior' means one lot of letters goes inside another (some letters go on the outside of others).
'trace' inserted inside 'unable' is 'UNTRACEABLE'.
'is' is the link.
Can you help me to learn more?
(Another definition for untraceable that I've seen is " not to be found".)