Royal husband given reminder about card game (6)
I believe the answer is:
euchre
'card game' is the definition.
(euchre is a kind of card game)
'royal husband given reminder about' is the wordplay.
'royal' becomes 'er' (I've seen this in other clues**).
'husband' becomes 'h'.
'given' means one lot of letters go next to another.
'reminder' becomes 'cue' (I've seen this before).
'about' is a reversal indicator.
'er'+'h'+'cue'='erhcue'
'erhcue' written backwards gives 'EUCHRE'.
(Other definitions for euchre that I've seen before include "American card-game" , "Game of cards" , "American card game" , "Outwit" , "Card game with best, right and left bowers" .)