Yankee in crimson reformed Old Boy network (8)
I believe the answer is:
cronyism
'old boy network' is the definition.
(I've seen this before)
'yankee in crimson reformed' is the wordplay.
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' is an insertion indicator.
'reformed' indicates anagramming the letters.
'crimson' anagrammed gives 'cronism'.
'y' going inside 'cronism' is 'CRONYISM'.
(Other definitions for cronyism that I've seen before include "The appointing of personal friends to jobs" , "Favouritism shown to friends and associates" , "Appointment of friends to jobs, regardless of qualifications" , "Dubious appointments" , "old boy network" .)