Member of the fam (3)
I think it could be either:
(Other definitions for bro that I've seen before include "Word used for male relative" , "US form of address" , "who may have a 28 [SIS]?" , "somewhere one feels close to" , "American greeting" .)
'member of the fam' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sis that I've seen before include "Little sibling" , "spies ..." , "Family member (informal)" , "Secret Intelligence Service (abbreviation)" , "Girl" .)