Resentful as the chap who's out of the race? (5)
I believe the answer is:
ratty
'resentful' is the definition.
Both the definition and answer are adjectives. Maybe there's an association between them I don't understand?
'the chap who's out of the race?' is the wordplay.
'the chap who' becomes 'ray' (I can't justify this - if you can you should believe this answer much more).
'out of' means one lot of letters goes inside another (some letters on the outside of others).
'the race?' becomes 'tt'.
'ray' going around 'tt' is 'RATTY'.
'as' is the link.
Can you help me to learn more?
(Other definitions for ratty that I've seen before include "Mole's friend (The Wind in the Willows)" , "Short" , "Waspish" , "Cross - character in "The Wind in the Willows"" , "Characteristic of pest" .)