Space after group of students returned to conservatory? (3,4)

'conservatory?' is the definition.
(I know that conservatory can be written as sun room)

'space after group of students returned' is the wordplay.
'space' becomes 'room' (enough space or room to do something).
'after' says to put letters next to each other.
'group of students' becomes 'NUS' (National Union of Students).
'returned' shows that the letters should be reversed in order.
'nus' reversed gives 'sun'.
'room' put after 'sun' is 'SUN-ROOM'.

'to' is the link.