Iowa doctor starting to introduce poetic measures (5)
I believe the answer is:
iambi
'poetic measures' is the definition.
(I've seen this in another clue)
'iowa doctor starting to introduce' is the wordplay.
'iowa' becomes 'IA' (standard US state two-letter abbreviation).
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'starting to' indicates taking the first letters.
The initial letter of 'introduce' is 'i'.
'ia'+'mb'+'i'='IAMBI'
(Other definitions for iambi that I've seen before include "Short-long metrical feet" , "Film theatre" , "Feet of two syllables (one short and one long)" , "Metrical units with alternating long and short syllables" , "Poetic feet" .)