Small change affected her plans (8)
I believe the answer is:
shrapnel
'small change' is the definition.
(I've seen this before)
'affected her plans' is the wordplay.
'affected' indicates an anagram.
'her'+'plans'='herplans'
'herplans' is an anagram of 'SHRAPNEL'.
(Other definitions for shrapnel that I've seen before include "Bits of an exploded shell" , "Exploding shell fragments" , "Bits of shelling" , "Bomb or shell fragments" , "Fragments from exploded shell" .)