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 am 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 can't justify this - if you can you should give a lot more credence to this answer).
'oxen' going around '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" .)