Cattle securing tails on violently passing gas (6)
I believe the answer is:
oxygen
'violently passing gas' is the definition.
'oxygen' can be an answer for 'gas' (I've seen this before). I'm not certain of the 'violently passing' bit.
'cattle securing tails' is the wordplay.
'cattle' becomes 'oxen' (type of cattle).
'securing' indicates putting letters inside.
'tails' becomes 'yg' (I am not sure about this - if you are sure you should believe this answer much more).
'oxen' enclosing 'yg' is 'OXYGEN'.
'on' is the link.
Can you help me to learn more?
(Other definitions for oxygen that I've seen before include "Gas discovered by Joseph Priestley, d. 1804" , "A combustible element" , "Gas essential to breathing" , "Life-giving gas" , "Gas necessary for life" .)