Provider of support, but no backup (5)
I believe the answer is:
stool
'support but no backup' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'provider of' is the wordplay.
I cannot really see how this works, but
'of' could be 'o' and 'o' is found in the answer.
The remaining letters 'stol' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stool that I've seen before include "item of furniture here" , "Armless seat" , "Motion" , "place butt on one?" , "Small seat" .)