Senseless how squabble ends (5)
I believe the answer is:
inane
'senseless' is the definition.
(I've seen this in another clue)
'how squabble ends' is the wordplay.
'how' becomes 'ina' (I can't explain this - if you can you should believe this answer much more).
'squabble' becomes 'niggle' (synonyms).
'ends' suggests removing the centre.
'niggle' with its centre taken out is 'ne'.
'ina'+'ne'='INANE'
Can you help me to learn more?
(Other definitions for inane that I've seen before include "Absurd" , "Unintelligent" , "Witless and pointless" , "Empty-headed" , "Silly, witless" .)