Money put into West End’s opening show (7)
I believe the answer is:
matinee
'show' is the definition.
(matinee is a kind of show)
'money put into west end's opening' is the wordplay.
'money' becomes 'tin' (old-fashioned slang term for money).
'put into' indicates putting letters inside.
'west' becomes 'Mae' (actress Mae West).
'opening' says to take the initial letters.
The first letter of 'ends' is 'e'.
'tin' going inside 'mae' is 'matine'.
'matine'+'e'='MATINEE'
(Other definitions for matinee that I've seen before include "Afternoon performance (of play etc)" , "Play, perhaps" , "early "performance"" , "Daytime performance of play etc" , "Afternoon show" .)