What makes hedges ultimately neater? (8)
I believe the answer is:
strimmer
'what' is the definition.
I know nothing about this answer so I can't tell whether this works.
'hedges ultimately neater?' is the wordplay.
'hedges ultimately' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'neater?' becomes 'trimmer' ('trim' can be a synonym of 'neat').
's'+'trimmer'='STRIMMER'
'makes' acts as a link.
(Other definitions for strimmer that I've seen before include "Brush cutter" , "Garden equipment" , "Gardening implement" , "Cutter for rough grass etc" , "Machine for cutting grass edges" .)