Ram not treated by head nurse (6)
I believe the answer is:
matron
'head nurse' is the definition.
(synonyms)
'ram not treated' is the wordplay.
'treated' indicates an anagram.
'ram'+'not'='ramnot'
'ramnot' with letters rearranged gives 'MATRON'.
'by' is the link.
(Other definitions for matron that I've seen before include "Old woman" , "One used to be in charge of hospital nurses" , "Senior nursing officer of old" , "Nurses' manager" , "Middle-aged or elderly married woman" .)