Ran up to house for class (7)
I believe the answer is:
seminar
'for class' is the definition.
(seminar is a kind of class)
'ran up to house' is the wordplay.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'house' becomes 'semi' (short for semi-detached).
'ran' backwards is 'nar'.
'nar' put after 'semi' is 'SEMINAR'.
(Other definitions for seminar that I've seen before include "Marines (anag.)" , "Short intensive study course for marines" , "Training meeting" , "Symposium" , "workshop" .)