THEME:   T substituted for E in phrases   
GOOD ONES:     Course that covers crop circles?   PLAN
T GEOMETRY   
Blast off?   STAR
T INTO SPACE   
Bread for burritos?   DINERO   
They're stuck in corners   STAMPS   
ESPN figures   STATS [not broadcasters]   
One in a pack?   LIE ["pack of lies"]   
English channel   THE BBC ["The Beeb" didn't fit so I thought I was on the wrong track]   
Page of music   PATTI   
Pick in a trick   CARD [I like the sound.  George Carlin, as a DJ, said "A pick to make you sick" and then mimicked a horrid rock song.]      
BTW:   Guiding principles   CREEDS [CREEDS are beliefs, not guides]      
Water, chemically  
 HOH [not in the school I went to.  But change HOH to HOE and PALE to PALS {Across} leaving TESTA {Down}]      
ESOS is never used in English.         
RATING:    
 
 
Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun