Increase tax in confused battle, member must go (7)
I believe the answer is:
elevate
'increase' is the definition.
'tax in confused battle member must go' is the wordplay.
'tax' becomes 'VAT' (Value-Added Tax).
'in' means one lot of letters goes inside another.
'confused battle' becomes 'melee' (a melee is a confused fight).
'member' becomes 'm' (political abbreviation).
'must go' suggests deleting specific letters.
'vat' put within 'melee' is 'melevate'.
'melevate' with 'm' taken out is 'ELEVATE'.
(Other definitions for elevate that I've seen before include "Raise high or promote" , "Put on a pedestal" , "Lift to higher place or position" , "Raise or lift" , "'Raise, upgrade (7)'" .)