Butcher kept a sow for soft underbelly (4,4)
I believe the answer is:
weak spot
'soft underbelly' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'butcher kept a sow' is the wordplay.
'butcher' indicates an anagram.
'kept'+'a'+'sow'='keptasow'
'keptasow' anagrammed gives 'WEAK SPOT'.
'for' is the link.
Can you help me to learn more?
(Other definitions for weak spot that I've seen before include "'Your area of vulnerability (4,4)'" , "Area in which one is not knowledgeable" , "Area of deficient knowledge" , "Achilles heel?" , "Gap in knowledge" .)