Some Brits oddly skipped this clue -- two upset (5)
I believe the answer is:
welsh
'some brits' is the definition.
(people from Wales)
'oddly skipped this clue two upset' is the wordplay.
'oddly skipped' indicates alternate letters (letters in odd-numbered positions removed).
'upset' is a reversal indicator.
'this'+'clue'+'two'='thiscluetwo'
The alternating letters of 'thiscluetwo' are 'hslew'.
'hslew' backwards is 'WELSH'.
(Other definitions for welsh that I've seen before include "and 14 Down: Melted cheese on toast" , "Nationality of Dai or Ivor" , "Native to, eg, Cardiff" , "From a western part of Britain" , "Fail to pay debt" .)