Go into hiding (3,3)
I believe the answer is:
lie low
'go into hiding' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lie low that I've seen before include "Conceal oneself or one's intentions" , "Stay out of sight, hide horizontally?" , "Remain unobtrusive - in prone posture?" , "Conceal oneself, don't be conspicuous" , "Conceal oneself, don't make intentions known" .)