... enthusiastic about covering Queen for opening musical piece (5)
I believe the answer is:
intro
'opening musical piece' is the definition.
'intro' can be an answer for 'piece' (intro is a kind of piece). I'm not certain of the 'opening musical' bit.
'enthusiastic about covering queen' is the wordplay.
'enthusiastic about' becomes 'into' (into can mean interested in or enthusiastic about).
'covering' is an insertion indicator.
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'into' enclosing 'r' is 'INTRO'.
'for' is the link.
Can you help me to learn more?
(Other definitions for intro that I've seen before include "One starts" , "Lead" , "starter" , "Opening notes" , "overture" .)