Financial support (6)
(Other definitions for upkeep that I've seen before include "Cost of support" , "payments?" , "Peek up at the maintenance" , "Cost of maintenance, say household" , "Running costs" .)
'financial support' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aid that I've seen before include "technique that can produce pregnancy" , "charity" , "Help or support" , "A hand" , "assistant" .)