Becomes unhinged at shelter when this is put on chair (5,5)
I believe the answer is:
loose cover
'this is put on chair' is the definition.
The definition suggests a singular noun which matches the answer.
'becomes unhinged at shelter' is the wordplay.
I cannot quite understand how this works, but
'shelter' could be 'cover' (I've seen this before) and 'cover' is found within the answer.
The remaining letters 'loose' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'when' is the link.
Can you help me to learn more?
(Another definition for loose cover that I've seen is " What goes over chair".)