Character, fashion legend, principally, is a person to emulate (4,5)
I believe the answer is:
role model
'a person to emulate' is the definition.
(someone to imitate or emulate)
'character fashion legend principally' is the wordplay.
I cannot really understand how this works, but
'character' could be 'role' (synonyms) and 'role' is present in the answer.
'fashion' could be 'model' (I've seen this before) and 'model' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'is' acts as a link.
Can you help me to learn more?
(Other definitions for role model that I've seen before include "A worthy person" , "One whose example should be followed" , "good example to follow" , "One looked up to" , "Someone looked up to" .)