Doctor abandons fight with current mammal (5)
I believe the answer is:
coati
'mammal' is the definition.
(coati is a kind of mammal)
'doctor abandons fight with current' is the wordplay.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'abandons' is a deletion indicator.
'fight' becomes 'combat' (combat is a kind of fight).
'with current' becomes 'i' (symbol for electric current. I am not sure about the 'with' bit.).
'combat' with 'mb' taken away is 'coat'.
'coat'+'i'='COATI'
(Other definitions for coati that I've seen before include "S. and Central American raccoon-like animal" , "Furry animal" , "wild animal" , "Tropical animal" , "omnivorous mammal" .)