Cattle herd runs away from farm building (7)
I believe the answer is:
cowshed
'farm building' is the definition.
(cowshed is a kind of farm building)
'cattle herd runs away' is the wordplay.
'cattle' becomes 'cows' ('cows' can be a synonym of 'cattle').
'runs' becomes 'r' (cricket abbreviation).
'away' is a deletion indicator.
'herd' with 'r' taken out is 'hed'.
'cows'+'hed'='COWSHED'
'from' is the link.
(Other definitions for cowshed that I've seen before include "Byre" , "Shelter for cattle" , "farm building" , "shanty" .)