1 Often, straighten out. uncurl, untangle, disentangle, unsnarl, unravel, unkink; clear (up), settle, resolve, sort out, set or put straight or right or to rights, correct, adjust, rectify:
She decided to have her hair straightened. They are busy straightening out the matter of father's will.
2 Often, straighten out. reform, rehabilitate, organize, reorganize:
Perhaps psychotherapy will straighten him out.
3 Often, straighten out or up. tidy (up), arrange, rearrange, neaten, spruce up, put in order, clean (up):
Would you help me straighten up the place before you leave?