Thoroughness in dicing eel another way (9)
I believe the answer is:
diligence
'thoroughness' is the definition.
(thesaurus)
'dicing eel another way' is the wordplay.
'another way' indicates an anagram.
'dicing'+'eel'='dicingeel'
'dicingeel' is an anagram of 'DILIGENCE'.
'in' is the link.
(Other definitions for diligence that I've seen before include "It takes steady application" , "that could be due?" , "dedication" , "Old stagecoach" , "Thoroughgoing application" .)