Friend friendly starting late (4)
I believe the answer is:
ally
'friend' is the definition.
('ally' can be a synonym of 'friend')
'friendly starting late' is the wordplay.
'friendly' becomes 'pally' ('pally' can be similar in meaning to 'friendly').
'starting late' means to remove the first letter (the word starts later than the beginning).
'pally' with its initial letter removed is 'ALLY'.
(Other definitions for ally that I've seen before include "often helpful when cluing adverbs" , "support" , "Band together" , "Team up" , "Comrade in arms" .)