Foremost of stars to encourage person associated with the theatre (7)
I believe the answer is:
surgeon
'person associated with the theatre' is the definition.
I can't judge whether this definition defines the answer.
'foremost of stars to encourage' is the wordplay.
'foremost of' indicates taking the first letters.
'to encourage' becomes 'urgeon' (urging on is a kind of encouraging).
The first letter of 'stars' is 's'.
's'+'urgeon'='SURGEON'
Can you help me to learn more?
(Other definitions for surgeon that I've seen before include "Operating medical practitioner" , "Doctor with cutting tools" , "Doctor in the navy" , "Theatre worker" , "Performer of operations" .)