First sign (7)
I believe the answer is:
I believe this is a double definition.
'first' is the first definition.
(similar in meaning)
'sign' is the second definition.
(initial can mean to sign with an initial)
(Other definitions for initial that I've seen before include "Sign" , "Let; rent" , "First home, corgi, ultimately, wagging tail" , "Name's first letter" , "First letter of a name" .)