Not sharp (5)
I believe the answer is:
blunt
'not sharp' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for blunt that I've seen before include "Frank and forthright" , "Forthright in manner" , "Dull or tactless" , "Dull - outspoken - spy" , "Frank - Soviet spy, d. 1983" .)