Show group of animals briefly returned and put in a new pen (7)

'put in a new pen' is the definition.

'show group of animals briefly returned' is the wordplay.
'show' becomes 'demo' (I've seen this before**).
'group of animals' becomes 'herd' (I've seen this before).
'briefly' means to remove the last letter.
'returned' shows that the letters should be reversed in order.
'herd' with its final letter taken off is 'her'.
'demo'+'her'='demoher'
'demoher' in reverse letter order is 'REHOMED'.

'and' acts as a link.