Measure taken so long as one stands for it (6)
I believe the answer is:
height
'measure' is the definition.
(height is a kind of measure)
'so long as one stands for it' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
'as' could be 'eg' (both can introduce an example) and 'eg' is present in the remaining letters.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'taken' is the link.
Can you help me to learn more?
(Other definitions for height that I've seen before include "Altitude or elevation" , "Measurement from base to top" , "size up?" , "Dimension upwards" , "Dimension from top to bottom" .)