This fellow's a social being, working on a satellite (7)
I believe the answer is:
antonio
'this fellow's a' is the definition.
The definition suggests a singular noun which matches the answer.
'social being working on a satellite' is the wordplay.
'social being working' becomes 'anton' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' means one lot of letters go next to another.
'a satellite' becomes 'Io' (Io is a moon of Jupiter).
'anton'+'io'='ANTONIO'
Can you help me to learn more?
(Other definitions for antonio that I've seen before include "sea captain in Twelfth Night" , "One contracted for a pound" , "A notion about The Merchant of Venice" , "-- Vivaldi, composer" , "Name of the Merchant of Venice who borrowed money" .)