Rumpus, not the first, about tax being put up (7)
I believe the answer is:
elevate
'being put up' is the definition.
(I've seen this before)
'rumpus not the first about tax' is the wordplay.
'rumpus' becomes 'melee' (I've seen this before).
'not the first' means to remove the first letter.
'about' is an insertion indicator.
'tax' becomes 'vat' (British sales tax).
'melee' with its initial letter taken away is 'elee'.
'elee' placed around 'vat' is 'ELEVATE'.
(Other definitions for elevate that I've seen before include "Lift to higher place or position" , "Lift up or ennoble" , "Hoist" , "Raise to a higher position" , "Put on a pedestal" .)