Let off the hook perhaps by newsgroup losing rows (5)
I believe the answer is:
unpeg
'perhaps by newsgroup losing rows' is the definition.
I can't tell whether this definition defines the answer.
'let off the hook' is the wordplay.
'let off' becomes 'un' (I can't explain this - if you can you should believe this answer much more).
'the hook' becomes 'peg' (I've seen this before).
'un'+'peg'='UNPEG'
Can you help me to learn more?
(Other definitions for unpeg that I've seen before include "Remove (clothes from a washing line)" , "Take down from the line" , "no longer freeze" , "Detach" , "free" .)