Enemy in retreat, safe to move around -- relax (4,3)
I believe the answer is:
ease off
'relax' is the definition.
(thesaurus)
'enemy in retreat safe to move around' is the wordplay.
'enemy' becomes 'foe' (I've seen this before).
'in retreat' is a reversal indicator.
'to move' indicates anagramming the letters.
'around' is an insertion indicator.
'foe' written backwards gives 'eof'.
'safe' anagrammed gives 'easf'.
'eof' going into 'easf' is 'EASE OFF'.
(Other definitions for ease off that I've seen before include "relieve tension" , "relent" , "Throttle back" , "Remove some pressure" , "Slow down" .)