Something useful — like a matching collection? (5)
I believe the answer is:
asset
'something useful' is the definition.
(I've seen this before)
'like a matching collection?' is the wordplay.
'like' becomes 'as'.
'a matching collection?' becomes 'set' (I've seen this in another clue).
'as'+'set'='ASSET'
(Other definitions for asset that I've seen before include "Something well worth having" , "Useful or valuable quality or possession" , "Advantage, strength" , "Item conferring advantage" , "Item of property" .)