Shows Tate Modern's bizarre point (12)
I believe the answer is:
demonstrates
'shows' is the definition.
(demonstrating is a kind of showing)
'tate modern's bizarre point' is the wordplay.
'bizarre' is an anagram indicator.
'point' becomes 's' (S is an example).
'tate'+'moderns'='tatemoderns'
'tatemoderns' anagrammed gives 'demonstrate'.
'demonstrate'+'s'='DEMONSTRATES'
(Other definitions for demonstrates that I've seen before include "kicks up a fuss" , "Shows" .)