False rumour an eccentric put about (6)
I believe the answer is:
canard
'false rumour' is the definition.
(I've seen this before)
'an eccentric put about' is the wordplay.
'eccentric put' becomes 'card' (I am not sure about this - if you are sure you should believe this answer much more).
'about' means one lot of letters goes inside another.
'an' placed into 'card' is 'CANARD'.
Can you help me to learn more?
(Other definitions for canard that I've seen before include "False rumour, originally from France" , "A false rumour, originally French" , "'False report, hoax (6)'" , "A false rumour from France? (6)" , "rumour that's false" .)