Bachelor leaves dog something valuable (5)
I believe the answer is:
asset
'something valuable' is the definition.
(I've seen this before)
'bachelor leaves dog' is the wordplay.
'bachelor' becomes 'b' (abbreviation e.g. BA=Bachelor of Arts).
'leaves' suggests deleting specific letters.
'dog' becomes 'basset' (type of dog).
'basset' with 'b' taken away is 'ASSET'.
(Other definitions for asset that I've seen before include "One bringing benefit" , "Useful or valuable quality or possession" , "Valuable item" , "Tessa (anag)" , "A useful thing l" .)