A Bachelor of Medicine getting one on one's feet (5)
I believe the answer is:
iambi
'feet' is the definition.
(iamb is a kind of foot)
'a bachelor of medicine getting one on one's' is the wordplay.
'bachelor of medicine' becomes 'mb' ('MB' can be a synonym of 'bachelor of medicine').
'getting' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'on' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'a' put next to 'mb' is 'amb'.
'amb' after 'i' is 'iamb'.
'iamb'+'i'='IAMBI'
(Other definitions for iambi that I've seen before include "Poetic feet" , "Metrical units with alternating long and short syllables" , "Metrical patterns" , "Feet of two syllables (one short and one long)" , "Poetic pieces" .)