Usually like an officer getting to reign (2,1,7,4)
I believe the answer is:
as a general rule
'usually' is the definition.
(I've seen this before)
'like an officer getting to reign' is the wordplay.
'like' becomes 'as'.
'an' becomes 'a'.
'officer' becomes 'general' (general is a kind of officer).
'getting to' means one lot of letters go next to another.
'reign' becomes 'rule' (synonyms).
'as'+'a'+'general'+'rule'='AS A GENERAL RULE'
(Other definitions for as a general rule that I've seen before include "emulate Franco?" , "Normally" , "for the most part" , "usually" .)