Gas ring clipped a spaceman (7)
I believe the answer is:
gagarin
'a spaceman' is the definition.
(I have seen 'old spaceman' mean 'gagarin' so perhaps 'spaceman' could also mean 'gagarin')
'gas ring clipped' is the wordplay.
'gas' becomes 'gaga' (I can't explain this - if you can you should give a lot more credence to this answer).
'clipped' means to remove the last letter (the word is shortened or clipped).
'ring' with its last letter taken off is 'rin'.
'gaga'+'rin'='GAGARIN'
Can you help me to learn more?
(Other definitions for gagarin that I've seen before include "old spaceman" , "circumnavigator" , "Yuri --, cosmonaut" , "Yuri ......, first Russian into space" , "Yuri . . . . . . . made the first manned space flight" .)