Some mint, about pint, mashed (6)
I believe the answer is:
catnip
'some mint' is the definition.
(I've seen this before)
'about pint mashed' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa').
'mashed' indicates anagramming the letters.
'pint' is an anagram of 'tnip'.
'ca'+'tnip'='CATNIP'
(Other definitions for catnip that I've seen before include "Puss would like that" , "Strong-smelling herb" , "Herb of the mint family, attractive to some pets" , "Kitty likes that!" , "Feline attractor (I, not E)" .)