Volatile chemical bonds without shell (5)
I believe the answer is:
ether
'volatile chemical' is the definition.
(ether is volatile)
'bonds without shell' is the wordplay.
'bonds' becomes 'tethers'.
'without shell' indicates the central letters (the word's 'shell' is removed).
The middle of 'tethers' is 'ETHER'.
(Other definitions for ether that I've seen before include "Volatile organic liquid once used as a general anaesthetic" , "Clear upper air" , "Medium supposedly" , "Solvent; clear sky (poet.)" , "Type of chemical" .)