Underwriter (7)
'underwriter?' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for subscriber that I've seen before include "One showing approval of idea" , "paid-up customer?" , "One on the telephone" , "underwriter?" .)
'underwriter' is the definition.
(I know that underwriter can be written as insurer)
This is the entire clue.
(Other definitions for insurer that I've seen before include "Loss adjuster's employer" , "Saga?" , "One offering cover" , "Is rerun (anag)" , "Underwriter of risks" .)