Exploiting lots about hiding old piece of furniture (7,5)
I believe the answer is:
milking stool
'piece of furniture' is the definition.
(milking stool is a kind of piece of furniture)
'exploiting lots about hiding old' is the wordplay.
'exploiting' becomes 'milking' (milking is a kind of exploiting).
'about' says the letters should be written backwards.
'hiding' indicates putting letters inside.
'old' becomes 'o' (abbreviation).
'lots' written backwards gives 'stol'.
'stol' enclosing 'o' is 'stool'.
'milking'+'stool'='MILKING-STOOL'
(Another definition for milking stool that I've seen is " seat".)