In focus, a general practice (5)
I believe the answer is:
usage
'practice' is the definition.
(usage is a kind of practice)
'in focus a general' is the wordplay.
'in' indicates the answer is hidden within the clue.
'USAGE' is hidden in the letters of 'focus a general'.
(Other definitions for usage that I've seen before include "Customary way in which language is spoken or written" , "Common practice" , "Way of employing" , "Particular meaning of a word" , "Silly little thing" .)