WordNet (r) 3.0 (2006):

straighten out
    v 1: settle or put right; "we need to iron out our
         disagreements" [syn: iron out, straighten out, put
         right]
    2: extricate from entanglement; "Can you disentangle the cord?"
       [syn: disentangle, unsnarl, straighten out] [ant:
       entangle, mat, snarl, tangle]
    3: change for the better; "The lazy student promised to reform";
       "the habitual cheater finally saw the light" [syn: reform,
       straighten out, see the light]
    4: make straight [syn: straighten, straighten out]
    5: make free from confusion or ambiguity; make clear; "Could you
       clarify these remarks?"; "Clear up the question of who is at
       fault" [syn: clear, clear up, shed light on,
       crystallize, crystallise, crystalize, crystalise,
       straighten out, sort out, enlighten, illuminate,
       elucidate]
    6: put (things or places) in order; "Tidy up your room!" [syn:
       tidy, tidy up, clean up, neaten, straighten,
       straighten out, square away]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "straighten out":
   accommodate, acculturate, adjust, admonish, advance, ameliorate,
   amend, arrange, better, boost, bring forward, bring to book,
   bring to terms, call to account, chastise, chide, civilize, close,
   close with, compose, conclude, correct, disentangle, edify,
   educate, elevate, emend, enhance, enlighten, enrich, extend,
   fatten, favor, fix, flatten, forward, foster, go straight,
   have words with, improve, improve upon, lard, lecture, lift,
   make an improvement, make peace, make up, meliorate, mend, nurture,
   objurgate, promote, put straight, raise, rate, rebuke, rectify,
   refine upon, reform, reprehend, reprimand, reprove, scold,
   set down, set straight, settle, settle with, sit up, smooth,
   socialize, spank, stand up, straighten, straighten up, take down,
   take to task, transfigure, transform, unbend, uncurl, unkink,
   unsnarl, upbraid, upgrade, uplift, work out