Went too far, with show mostly presented in open (8)
I believe the answer is:
overshot
'went too far' is the definition.
(I've seen this before)
'show mostly presented in open' is the wordplay.
'mostly' means to remove the last letter.
'presented in' indicates putting letters inside.
'open' becomes 'overt' ('overt' is associated in meaning with 'open'**).
'show' with its last letter removed is 'sho'.
'sho' placed within 'overt' is 'OVERSHOT'.
'with' acts as a link.
(Other definitions for overshot that I've seen before include "Went too far" , "Passed beyond the mark or runway" , "Went past the mark" , "Exceeded" , "needed to pull back?" .)