Music for an extraterrestrial, possibly in outer space (6)
I believe the answer is:
rocket
'in outer space' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'music for an extraterrestrial' is the wordplay.
'music' becomes 'rock' (rock music).
'for' says to put letters next to each other.
'an extraterrestrial' becomes 'et' (I've seen this in other clues).
'rock'+'et'='ROCKET'
'possibly' is the link.
Can you help me to learn more?
(Other definitions for rocket that I've seen before include "Salad plant - shoot up" , "Space missile" , "high-flier" , "High speed steam engine (1829)" , "Firework - salad plant" .)