YES

TRS:

  f(f(a())) -> c()

linear polynomial interpretations on N:

  f_A(x1) = x1 + 1
  f#_A(x1) = x1 + 1
  a_A = 2
  a#_A = 2
  c_A = 1
  c#_A = 1

precedence:

  a > f > c