Hospital period leaving doctor initially in charge of arms (8)
I believe the answer is:
heraldic
'of arms' is the definition.
'hospital period leaving doctor initially in charge' is the wordplay.
'hospital' becomes 'h' (abbreviation for hospital on maps).
'period' becomes 'era' (era is a kind of period).
'initially' suggests taking the first letters.
'in charge' becomes 'ic' (abbreviation for 'in charge').
The first letters of 'leaving doctor' is 'ld'.
'h'+'era'+'ld'+'ic'='HERALDIC'
(Other definitions for heraldic that I've seen before include "Of family crests" , "Relating to officers who register genealogies" , "of the coat of arms" , "Relating to coats of arms etc" , "Of armorial bearings" .)