Info supplied by senior officer, briefly (3)
I believe the answer is:
gen
I believe this is a double definition.
'info' is the first definition.
(gen is a kind of info)
'senior officer briefly' is the second definition.
(abbreviation for general)
'supplied by' acts as a link.
(Other definitions for gen that I've seen before include "Knowledge" , "Information (colloq.)" , "Lowdown (sl.)" , "Information yielded" , "'Information, colloquially (3)'" .)