The month I’m a graduate, I get hammered (7)
I believe the answer is:
marimba
'i get hammered' is the definition.
(musical instrument played with mallets)
'the month i'm a graduate' is the wordplay.
'the month' becomes 'Mar' (short for March).
'a graduate' becomes 'BA' (someone with a Bachelor of Arts degree).
'mar'+'im'+'ba'='MARIMBA'
(Other definitions for marimba that I've seen before include "Xylophone-like instr." , "Xylophone-like instrument from Africa" , "Deep toned percussion instrument" , "African xylophone" , "Latin American instrument like a xylophone" .)