Curious saint called Elmo initially (7)
I believe the answer is:
strange
'curious' is the definition.
(similar in meaning)
'saint called elmo initially' is the wordplay.
'saint' becomes 'st' (abbreviation).
'called' becomes 'rang' (called on the phone).
'initially' suggests taking the first letters.
The first letter of 'elmo' is 'e'.
'st'+'rang'+'e'='STRANGE'
(Other definitions for strange that I've seen before include "Curious" , "Odd kind of garnets" , "Peculiar; Morse's boss" , "Offbeat" , "as quarks in certain hadrons" .)