Virile army doctor ringing a key hospital (5)
I believe the answer is:
macho
'virile' is the definition.
(I've seen this before)
'army doctor ringing a key hospital' is the wordplay.
'army doctor' becomes 'mo' (medical officer).
'ringing' means one lot of letters goes inside another.
'key' becomes 'c' (I've seen this in other clues).
'hospital' becomes 'h' (abbreviation for hospital on maps).
'a'+'c'+'h'='ach'
'mo' enclosing 'ach' is 'MACHO'.
(Other definitions for macho that I've seen before include "Ultra-masculine" , "Ramboesque" , "Like aggressive male" , "Laddish" , "Spiny lobster" .)