Standing up to selectors dismissing loss (5)
I believe the answer is:
erect
'standing' is the definition.
('erect' can be similar in meaning to 'standing')
'up to selectors dismissing loss' is the wordplay.
'up' is an anagram indicator.
'dismissing' is a deletion indicator.
'selectors' with 'loss' taken away is 'eectr'.
'eectr' is an anagram of 'ERECT'.
(Other definitions for erect that I've seen before include "Upright or vertical" , "Upstanding" , "Build, set up" , "Upright; construct" , "Found" .)