Go freakish when unwisely let out (6)
I believe the answer is:
toddle
'go freakish' is the definition.
I can't tell whether this definition defines the answer.
'when unwisely let out' is the wordplay.
'when' becomes 'odd' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'unwisely' indicates anagramming the letters.
'out' is an insertion indicator.
'let' with letters rearranged gives 'tle'.
'odd' placed inside 'tle' is 'TODDLE'.
Can you help me to learn more?
(Other definitions for toddle that I've seen before include "Move like an infant?" , "Walk unsteadily like a small child" , "Move like someone starting out on life" , "Aimless stroll" , "Walk like baby" .)