Possible spaces for bass, as featured in song (7)
I believe the answer is:
aquaria
'possible spaces for bass' is the definition.
I can't judge whether this definition defines the answer.
'as featured in song' is the wordplay.
'as' becomes 'qua' ('qua' is a Latin term meaning 'in the capacity of').
'featured in' means one lot of letters goes inside another.
'song' becomes 'aria' (piece of music in an opera).
'qua' inserted within 'aria' is 'AQUARIA'.
Can you help me to learn more?
(Other definitions for aquaria that I've seen before include "display tanks" , "Tanks or buildings for fish" , "Transparent fish tanks" .)