Maxim used in skinhead agenda (5)
I believe the answer is:
adage
'maxim' is the definition.
(I've seen this before)
'in skinhead agenda' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ADAGE' is hidden within 'skinhead agenda'.
'used' is the link.
(Other definitions for adage that I've seen before include "Wise old saying" , "Saying, saw" , "Old saw" , "Old saying; proverb" , "Slogan" .)