YES

(VAR x)
(RULES
  a(a(a(x))) -> a(a(x))
  b(x) -> a(x)
  c(x) -> a(x)
)

(COMMENT
Termination is shown by KBO with weight

  w0 = 1
  w(a) = 1
  w(b) = 3
  w(c) = 2

and precedence:

  a > c > b
)