Observers initially imply, wrongly, Charlie is like a legendary athlete (7)
I believe the answer is:
olympic
'like a legendary athlete' is the definition.
I can't judge whether this defines the answer.
'observers initially imply wrongly charlie' is the wordplay.
'initially' says to take the initial letters.
'wrongly' indicates an anagram.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
The initial letter of 'observers' is 'o'.
'imply' is an anagram of 'lympi'.
'o'+'lympi'+'c'='OLYMPIC'
'is' is the link.
Can you help me to learn more?
(Other definitions for olympic that I've seen before include "Relating to two thousand and twelve London games" , "of certain events" , "These games are held every four years" , "International sporting event" , "Of a worldwide sporting movement" .)