Shade put up outside milliner's shop missing base, oops (5,4,2)
I believe the answer is:
thats torn it
'shade put up outside milliner's' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'shop missing base oops' is the wordplay.
I cannot quite understand how this works, but
'shop' could be 'hat' (hat shop is a kind of shop) and 'hat' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for thats torn it that I've seen before include "Something has upset my plans!" , "Throw into jail" , "Blast" , "for God's sake!" , "All plans are now spoilt!" .)