Go in vain, perhaps, when there's a hush (6)
I believe the answer is:
vanish
'go' is the definition.
(I know that go is a kind of the vanish)
'vain perhaps when there's a hush' is the wordplay.
I cannot really understand how this works, but
an anagram of 'vain' is 'vani' which is within the answer.
'hush' could be 'sh' (both are used to tell someone to be quiet) and 'sh' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for vanish that I've seen before include "Disappear suddenly" , "Disappear (in a puff of smoke?)" , "Disappear or fade from sight" , "Cease to exist" , "Disappear completely" .)