King Welshman rejected for a card of lesser value (5)
I believe the answer is:
knave
'king' is the definition.
(thesaurus)
'welshman rejected for a card of lesser value' is the wordplay.
'welshman' becomes 'evan' (I've seen this before).
'rejected' says the letters should be written backwards.
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'a card of lesser value' becomes 'k' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'evan' back-to-front is 'nave'.
'nave' put after 'k' is 'KNAVE'.
Can you help me to learn more?
(Other definitions for knave that I've seen before include "Rascal; picture card" , "Jack - rogue" , "Jack - scoundrel" , "Jack - rotter" , "Varlet; Jack" .)