Friend of everybody ending in ignominy (4)
I believe the answer is:
ally
'friend' is the definition.
('ally' can be a synonym of 'friend')
'everybody ending in ignominy' is the wordplay.
'everybody' becomes 'all' (I've seen this before).
'ending in' indicates one should take the final letters.
The last letter of 'ignominy' is 'y'.
'all'+'y'='ALLY'
'of' is the link.
(Other definitions for ally that I've seen before include "Join - friend" , "One in cooperation with another" , "Friend in time of need" , "Friend and colleague" , "Join forces with" .)