Sorry tale of old boy on board, right-winger (3,5)
I believe the answer is:
sob story
'sorry tale' is the definition.
(I've seen this before)
'old boy on board right-winger' is the wordplay.
'old boy' becomes 'OB' (abbreviation for a private school 'old boy').
'on' is an insertion indicator.
'board' becomes 'ss' (I can't justify this - if you can you should believe this answer much more).
'right-winger' becomes 'Tory' (Tory is an example).
'ob' placed within 'ss' is 'sobs'.
'sobs'+'tory'='SOB-STORY'
'of' is the link.
Can you help me to learn more?
(Other definitions for sob story that I've seen before include "Tale intended to arouse pity" , "Tale of misfortune" , "unhappy tale" , "tale of woe" , "Plea for sympathy from Tory boss" .)