Supports people have when annoyed (5,2)
I believe the answer is:
backs up
'supports' is the definition.
('back up' can be a synonym of 'support')
'people have when annoyed' is the wordplay.
I cannot quite understand how this works, but
'people' could be 'backs' (back is a kind of person) and 'backs' is present in the answer.
The remaining letters 'up' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for backs up that I've seen before include "Supports" , "Stands by" , "what annoying people get" .)