Restricted way in which sulphur absorbed into volatile nebula (3,4)
I believe the answer is:
bus lane
'restricted way in' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'sulphur absorbed into volatile nebula' is the wordplay.
I cannot quite see how this works, but
'sulphur' could be 's' (synonyms) and 's' is found in the answer.
an anagram of 'nebula' is 'bulane' which is located in the left over letters.
No letters remain.
This explanation may well be incorrect...
'which' acts as a link.
Can you help me to learn more?
(Other definitions for bus lane that I've seen before include "prohibited carriageway" , "Road space reserved for public transport" , "Reserved section of road" , "coach may also use?" , "Dedicated section of road" .)