Money HQ about to be demolished (4)
I believe the answer is:
cent
'money' is the definition.
(eg denomination of dollars)
'hq about to be demolished' is the wordplay.
'hq' becomes 'centre' (centre can mean a headquarters or base).
'about' becomes 're' (common abbreviation for 'with reference to').
'to be demolished' indicates named letters should be taken away.
'centre' with 're' removed is 'CENT'.
(Other definitions for cent that I've seen before include "Small monetary unit" , "One-hundredth of the value of the basic unit" , "One-hundreth part of a currency" , "cheap at this price?" , "Little bit of money" .)