Moved furtively heading off, but didn't do anything (5)
I believe the answer is:
idled
'off but didn't do anything' is the definition.
I can't tell whether this definition defines the answer.
'moved furtively heading' is the wordplay.
'moved' becomes 'led' (leading is a kind of moving).
'furtively' becomes 'id' (I can't explain this - if you can you should give a lot more credence to this answer).
'heading' is a charade indicator (letters next to each other) (some letters go in front of or head others).
'led' put after 'id' is 'IDLED'.
Can you help me to learn more?
(Other definitions for idled that I've seen before include "Loafed, lazed about" , "Loitered" , "Did little or nothing" , "sat back" , "pottered" .)