I think your clerk has missed the point here. You have a Scheme of Delegation, agreed at the Annual Meeting, which defines the role of the Estates Committee as "to consider policy issues..." and "scrutinise the operation..." and "to make recommendations to the Council..." There is no mention of any power to spend money, whether budgeted or not. If the Council wishes the Committee to have delegated powers to spend in accordance with the Financial Regulations, add this to the delegated role of the committee. Job done!
For what it's worth, I've been involved in local government administration since 1984 and for the last 30 years, I have held various positions providing advice and support to councils and voluntary organisations in relation to cooperation and joint working.