Finish period of time in tea production (9)
I believe the answer is:
terminate
'finish' is the definition.
(I know that finish is a more specific form of the action terminate)
'period of time in tea production' is the wordplay.
'period of time' becomes 'term' (term is a kind of period of time).
'production' is an anagram indicator.
'tea' is an anagram of 'ate'.
'term'+'in'+'ate'='TERMINATE'
(Other definitions for terminate that I've seen before include "Stop" , "Kill off" , "Put an end to, discontinue" , "Bring to an end" , "Finalise" .)