This writer taking irregular tea in performance (7)
I believe the answer is:
matinee
'performance' is the definition.
(matinee is a kind of performance)
'this writer taking irregular tea in' is the wordplay.
'this writer' becomes 'me' (the person who wrote the clues).
'taking' indicates putting letters inside.
'irregular' indicates an anagram.
'tea'+'in'='teain'
'teain' with letters rearranged gives 'atine'.
'me' going around 'atine' is 'MATINEE'.
(Other definitions for matinee that I've seen before include "Afternoon showing of play" , "Afternoon performance (of play etc)" , "Daytime performance of play etc" , "First jackets" , "early "performance"" .)