In Pandemic can I immediately cure disease to return to the 7 card limit?
You can't do this, since you discard immediately if at any time you have more than 7 cards. From the rules:


  If you ever have more than 7 cards in hand (after first resolving any Epidemic cards you may have drawn), discard cards or play Event cards until you have 7 cards in hand (...).


Drawing epidemics is the only exception; those don't stay in your hand long enough to cause you to discard.

This is also mentioned under "commonly overlooked rules":


  Your hand limit applies immediately after getting a card from another player.


Note that the reminder text in the corner of the board might lead you astray here, saying:


  
  Take 4 actions
  Draw 2 cards
  
  Resolve epidemics
  Discard to 7 cards
  
  Draw Infection cards
  


You should read that as a reminder that you may need to discard then, not as an indication that you don't need to discard at other times.