Extract from Mandelstam poetry shows character (5)
I believe the answer is:
stamp
'character' is the definition.
(I've seen this in another clue)
'extract from mandelstam poetry shows' is the wordplay.
'extract from' indicates a hidden word (some letters extracted from the clue).
'STAMP' is hidden in the letters of 'mandelstam poetry shows'.
(Other definitions for stamp that I've seen before include "Bring one's foot down" , "Kind" , "Use a die; character" , "Official mark; bang (foot)" , "One has picture of Queen" .)