Fifteen minutes to gain control over military officer (13)
I believe the answer is:
quartermaster
'military officer' is the definition.
(quartermaster is a kind of military officer)
'fifteen minutes to gain control over' is the wordplay.
'fifteen minutes' becomes 'quarter' (I am not sure about this - if you are sure you should believe this answer much more).
'to gain control over' becomes 'master'.
'quarter'+'master'='QUARTERMASTER'
(Other definitions for quartermaster that I've seen before include "Army officer responsible for administration" , "Regimental officer responsible for accommodation, food etc" , "Naval offcer" , "Supply officer" , "Army ration keeper" .)