Characteristic memo (4)
I believe the answer is:
note
This clue is a double definition.
'characteristic' is the first definition.
(I've seen this before)
'memo' is the second definition.
(thesaurus)
(Other definitions for note that I've seen before include "Put down" , "Short informal letter" , "Crotchet or minim, perhaps" , "Record; memo" , "Do, re or mi?" .)