It’s great – double so, to go without nothing (3)
I believe the answer is:
big
'it's great' is the definition.
('big' can be a synonym of 'great')
'double so to go without nothing' is the wordplay.
'double so' becomes 'bi' (I can't justify this - if you can you should give a lot more credence to this answer).
'to' means one lot of letters go next to another.
'without' is a deletion indicator.
'nothing' becomes 'o' (looks like zero - 0).
'go' with 'o' taken out is 'g'.
'bi'+'g'='BIG'
Can you help me to learn more?
(Other definitions for big that I've seen before include "Massive" , "Important" , "Circus tent" , "Of considerable size" , "Sizeable" .)