Regular place to study protocol (7)
I believe the answer is:
uniform
'regular' is the definition.
(similar in meaning)
'place to study protocol' is the wordplay.
'place to study' becomes 'uni'.
'protocol' becomes 'form' (form can mean protocol or procedure).
'uni'+'form'='UNIFORM'
(Other definitions for uniform that I've seen before include "dress of a serving girl?" , "Flat" , "Consistent, unvarying" , "Codeword following Tango" , "Always the same, unvarying." .)