Backer on the Tube? (5)
I believe the answer is:
angel
I believe this is a double definition.
'backer' is the first definition.
(an angel is a financial backer)
'on the tube?' is the second definition.
(station on the London Underground ie the Tube)
(Other definitions for angel that I've seen before include "Old coin; theatre investor" , "Spiritual being - financial backer" , "Theatrical backer" , "Word linking cake and fish" , "One backing plays" .)