Commercial in which scene cut to scale (6)
I believe the answer is:
ascend
'scale' is the definition.
(I've seen this before)
'commercial in which scene cut' is the wordplay.
'commercial' becomes 'ad' (abbreviation for advertisement).
'in which' is an insertion indicator.
'cut' means to remove the last letter.
'scene' with its last letter removed is 'scen'.
'ad' placed around 'scen' is 'ASCEND'.
'to' is the link.
(Other definitions for ascend that I've seen before include "Travel upwards" , "Move upward" , "Make the top" , "Move upwards" , "rise in status" .)