Pair connected somehow more than usually liable to mishap (8-5)
I believe the answer is:
accident-prone
'more than usually liable to mishap' is the definition.
(likely to have accidents)
'pair connected somehow' is the wordplay.
'somehow' indicates an anagram.
'pair'+'connected'='pairconnected'
'pairconnected' with letters rearranged gives 'ACCIDENT-PRONE'.
(Other definitions for accident-prone that I've seen before include "Liable to have mishaps" , "Clumsy" , "Unusually susceptible to mishaps" , "Given to misadventure" , "Susceptible to mishap" .)