WordNet (r) 3.0 (2006):

get at
    v 1: reach or gain access to; "How does one access the attic in
         this house?"; "I cannot get to the T.V. antenna, even if I
         climb on the roof" [syn: access, get at]
    2: influence by corruption
    3: cause annoyance in; disturb, especially by minor irritations;
       "Mosquitoes buzzing in my ear really bothers me"; "It
       irritates me that she never closes the door after she leaves"
       [syn: annoy, rag, get to, bother, get at,
       irritate, rile, nark, nettle, gravel, vex,
       chafe, devil]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "get at":
   annex, approach, arrive at, arrive upon, ascertain, assure, bribe,
   buy, buy off, certify, cinch, clear up, clinch, come at, come upon,
   corrupt, decide, determine, dismiss all doubt, ensure, establish,
   fall upon, find out, fix, get hold of, get to, glom on to, grab,
   grease, grease the palm, hit upon, insure, lay hands on,
   light upon, make certain, make no doubt, make no mistake,
   make sure, make sure of, nail down, pay off, pitch upon, purchase,
   reach, reassure, remove all doubt, see that, see to it,
   set at rest, settle, sort out, strike upon, stumble on,
   stumble upon, suborn, take care of, take over, take possession,
   take up, tamper with, tickle the palm