Performance of pantomime ends in speech (9)
I believe the answer is:
operation
'performance' is the definition.
(I've seen this before)
'pantomime ends in speech' is the wordplay.
'ends' means to remove the middle letters.
'in' means one lot of letters goes inside another.
'speech' becomes 'oration' (oration is a kind of speech).
'pantomime' with its middle taken out is 'pe'.
'pe' inserted inside 'oration' is 'OPERATION'.
'of' is the link.
(Other definitions for operation that I've seen before include "Theatre procedure" , "In hospital procedure" , "running" , "Action; process" , "Act of surgery" .)