Choice surrounds era of some theatre job (9)
I believe the answer is:
operation
'some theatre job' is the definition.
'operation' can be an answer for 'job' (thesaurus). I'm not sure about the 'some theatre' bit.
'choice surrounds era' is the wordplay.
'choice' becomes 'option' (synonyms).
'surrounds' means one lot of letters goes inside another.
'option' placed around 'era' is 'OPERATION'.
'of' is the link.
Can you help me to learn more?
(Other definitions for operation that I've seen before include "battle" , "Surgical or military piece of work" , "Theatre procedure" , "management" , "Business" .)