Was a model for part of the weekend (3)
I believe the answer is:
sat
'part of the weekend' is the definition.
(abbreviation for Saturday)
'was a model' is the wordplay.
'was' becomes 'sa' (I am not sure about this - if you are sure you should believe this answer much more).
'a model' becomes 'T' (Ford Model T car).
'sa'+'t'='SAT'
'for' is the link.
Can you help me to learn more?
(Other definitions for sat that I've seen before include "nearly half a day" , "Was couch potato" , "Took a chair" , "Posed (for an artist)" , "Perched" .)