Cost-effective (10)
(Other definitions for economical that I've seen before include "Careful" , "Reasonable" , "Thrifty" , "Using little" , "Inexpensive" .)
'cost-effective' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for economic that I've seen before include "(Likely to be) profitable" , "Relating to careful financial management" , "Sparing with resources or money" , "Likely to bring a profit" , "Coo, mince! (anag.)" .)