She's all set to stray (6)
I believe the answer is:
stella
'she's' is the definition.
(I've seen this before)
'all set to stray' is the wordplay.
'to stray' indicates an anagram.
'all'+'set'='allset'
'allset' is an anagram of 'STELLA'.
(Other definitions for stella that I've seen before include "girl!" , "____ McCartney, fashion designer" , "- Gibbons (Cold Comfort Farm)" , "woman" , "Swift favourite" .)