Steer clear as every third of the steers ruminate (6)
I believe the answer is:
eschew
'steer clear as every' is the definition.
I can't tell whether this definition defines the answer.
'third of the steers ruminate' is the wordplay.
'third of the' becomes 'e' (3rd letter of 'the').
'steers' becomes 's' (this might be a standard abbreviation which I don't know about).
'ruminate' becomes 'chew' (I've seen this before).
'e'+'s'+'chew'='ESCHEW'
Can you help me to learn more?
(Other definitions for eschew that I've seen before include "Steer clear of" , "Ignore" , "Deliberately avoid" , "Avoid or abstain from, food or people" , "'Avoid, shun (6)'" .)