Avoid those — teach Harry to be brief (3,2,3,5)
I believe the answer is:
cut to the chase
'be brief' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'avoid those teach harry' is the wordplay.
'avoid' becomes 'cut' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'harry' is an anagram indicator (harry can mean to attack or spoil).
'those'+'teach'='thoseteach'
'thoseteach' with letters rearranged gives 'tothechase'.
'cut'+'tothechase'='CUT TO THE CHASE'
'to' is the link.
Can you help me to learn more?
(Other definitions for cut to the chase that I've seen before include "'Stop beating about the bush!'" , "Get to the point" , "Start discussing important matters" .)