Don’t split up tasty fragments! (4,3)
I believe the answer is:
Here is my best explanation:
'don't split' is the definition.
'up tasty fragments' is the subsidiary indication.
'fragments' indicates an anagram.
'uptasty' anagrammed gives 'stayput'.
(Other definitions for stay put that I've seen before include "Remain in place, don't move", "Remain in one place", "Stick around", "Don't move", "Informally, don't move - remain in situ" and "Remain unmoving".)