Artist and doctor: old, aggressive male (5)
I believe the answer is:
rambo
'aggressive male' is the definition.
(book and film character)
'artist and doctor old' is the wordplay.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'and' means one lot of letters go next to another.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'ra'+'mb'+'o'='RAMBO'
(Other definitions for rambo that I've seen before include "Stupidly aggressive type" , "Character given to mindless violence" , "Tough aggressive man" , "Brainless muscleman" , "Stallone film character" .)