Hard borders? Avoids making a decision (6)
I believe the answer is:
hedges
'avoids making a decision' is the definition.
(as in hedging one's bets)
'hard borders?' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'borders?' becomes 'edges' ('edge' can be a synonym of 'border').
'h'+'edges'='HEDGES'
(Other definitions for hedges that I've seen before include "Fences of bushes" , "Buys or sells protective security" , "Avoids answering" , "Living fences" , "guards" .)