Straying in herd can result in obstruction (9)
I believe the answer is:
hindrance
'obstruction' is the definition.
(I know that hindrance is a type of obstruction)
'straying in herd can result in' is the wordplay.
'straying' is an anagram indicator.
'result' is an anagram indicator (I've seen 'result of' mean this).
'in' indicates putting letters inside.
'can' anagrammed gives 'anc'.
'in'+'herd'='inherd'
'inherd' is an anagram of 'hindre'.
'hindre' placed around 'anc' is 'HINDRANCE'.
(Other definitions for hindrance that I've seen before include "Delay to overcome" , "Chain nerd up - it delays progress" , "Something that holds back" , "barrier" , "Block to progress" .)