Indecisive as to this neat arrangement (8)
I believe the answer is:
hesitant
'indecisive' is the definition.
(synonyms)
'to this neat arrangement' is the wordplay.
'arrangement' indicates an anagram.
'this'+'neat'='thisneat'
'thisneat' with letters rearranged gives 'HESITANT'.
'as' is the link.
(Other definitions for hesitant that I've seen before include "Not quick" , "Wavering" , "Indecisive" , "Uncertain, nervous" , "Pausing - undecided" .)