As a superstar, I had a cold heart (4)
I believe the answer is:
idol
'as a superstar' is the definition.
I can't tell whether this definition defines the answer.
'i had a cold heart' is the wordplay.
'i had' becomes 'i'd' (I'd).
'heart' indicates the central letters.
The central letters of 'cold' are 'ol'.
'id'+'ol'='IDOL'
Can you help me to learn more?
(Other definitions for idol that I've seen before include "Who's greatly respected" , "Superstar; graven image" , "Pop - - (TV)" , "Object of excessive adoration" , "Heathen god" .)