Enclosure for bird's bed (7)
I believe the answer is:
cockpit
'enclosure' is the definition.
(cockpit is a kind of enclosure)
'bird's bed' is the wordplay.
'bird' becomes 'cock' (I've seen this before).
'bed' becomes 'pit' (I've seen this in other clues).
'cock'+'pit'='COCKPIT'
'for' is the link.
(Other definitions for cockpit that I've seen before include "battlefield" , "Driver's compartment in a racing car" , "Pilot's compartment - scene of fighting" , "found in plane" , "Flightdeck" .)