Holding dog with no lead (5)
I believe the answer is:
asset
'holding' is the definition.
(I've seen this before)
'dog with no lead' is the wordplay.
'dog' becomes 'basset' (basset is a kind of dog).
'with no lead' means to remove the first letter.
'basset' with its first letter taken away is 'ASSET'.
(Other definitions for asset that I've seen before include "Something useful" , "Part of motor vehicle wheel" , "Valuable person" , "Useful thing or person" , "Useful item" .)