Bird mine in pilot's enclosure (7)
I believe the answer is:
cockpit
'pilot's enclosure' is the definition.
'cockpit' can be an answer for 'enclosure' (cockpit is a kind of enclosure). I am not sure about the 'pilot's' bit.
'bird mine' is the wordplay.
'bird' becomes 'cock' (cock is a kind of bird).
'mine' becomes 'pit' (as in a mining pit).
'cock'+'pit'='COCKPIT'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for cockpit that I've seen before include "found in plane" , "Driver's compartment in a racing car" , "Front section of a plane" , "Main venue" , "Racing driver's seat" .)