Large tin changed shape (8)
I believe the answer is:
triangle
'shape' is the definition.
(I know that triangle is a type of shape)
'large tin changed' is the wordplay.
'changed' is an anagram indicator.
'large'+'tin'='largetin'
'largetin' is an anagram of 'TRIANGLE'.
(Other definitions for triangle that I've seen before include "complex romantic situation?" , "Gable shape -- 1 across (anag)" , "Figure - percussion instrument" , "Three-sided percussion instrument" , "kitchen item" .)