THEME:   last word of a phrase relates to chess   
GOOD ONES:     Game where {& theme}   CHESS [should be "Game which…"]   
Stock market giant?   KNORR [they make soups and I suppose stock]      
BTW:   I can assume what PIN and FORK mean in chess, but as a player only as a boy they are unknown to me.      
Don't know why I am miffed when I am told to KEEP YOUR FORK.      
Confident way to solve crosswords   IN INK [for me it's not confidence but the desire to see contrast between newsprint and dark ink --- pencil blends]      
Flowery composition   ODE [no more so than any other LYRIC or an IDYLL, ROMANCE, EPISTOLARY, or an ESSAY about your Aunt Harriet]      
Part of a class act   SCHOOLMATE [clue is so far afield it's out of the stadium]      
RATING: 
 
   Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun