Be still turning up in a tasty concoction (4,3)
I believe the answer is:
stay put
'be still' is the definition.
(thesaurus)
'turning up in a tasty concoction' is the wordplay.
'turning' is a reversal indicator.
'in' indicates putting letters inside.
'concoction' is an anagram indicator.
'up' back-to-front is 'pu'.
'tasty' is an anagram of 'stayt'.
'pu' put inside 'stayt' is 'STAY PUT'.
(Other definitions for stay put that I've seen before include "Remain in one place" , "Remain in place, don't move" , "Stick around" , "Informally, don't move - remain in situ" , "Remain unmoving" .)