Do they give one short change indoors? (6)
I believe the answer is:
donors
'do they' is the definition.
The definition suggests a plural noun which matches the answer.
'give one short change indoors?' is the wordplay.
'give' becomes 'dors' (I am not sure about this - if you are sure you should believe this answer much more).
'short' means to remove the last letter.
'change' is an anagram indicator.
'indoors?' means one lot of letters goes inside another (indoors can mean inside or within).
'one' with its last letter taken off is 'on'.
'on' with letters rearranged gives 'no'.
'dors' placed around 'no' is 'DONORS'.
Can you help me to learn more?
(Other definitions for donors that I've seen before include "They give, money or blood" , "Givers as of blood" , "They give to others, maybe blood" , "presenters" , "They give, blood say" .)