Pay no attention to unfriendly bear
I believe the answer is:
cold shoulder
'pay no attention' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'unfriendly bear' is the wordplay.
'unfriendly' becomes 'cold' ('cold' can be similar in meaning to 'unfriendly').
'bear' becomes 'shoulder' (I've seen this before**).
'cold'+'shoulder'='COLD-SHOULDER'
'to' is the link.
Can you help me to learn more?
(Other definitions for cold shoulder that I've seen before include "Ignore" , "Ought to put in cooler!" , "Snub" , "Show indifference" , "Cut" .)