Number in temporary accommodation reduced (3)
I believe the answer is:
ten
'number' is the definition.
(ten is a kind of whole number)
'temporary accommodation reduced' is the wordplay.
'temporary accommodation' becomes 'tent' (I've seen this before).
'reduced' means to remove the last letter.
'tent' with its last letter removed is 'TEN'.
'in' is the link.
(Other definitions for ten that I've seen before include "Half a score" , "No of sides of a decagon" , "honour" , "Five times two" , "Base of decimal system" .)