Bird priest trapped in soft container (7)
I believe the answer is:
pelican
'bird' is the definition.
(pelican is a kind of bird)
'priest trapped in soft container' is the wordplay.
'priest' becomes 'eli' (biblical figure).
'trapped in' means one lot of letters goes inside another.
'soft' becomes 'p' (musical abbreviation for piano, 'soft').
'container' becomes 'can' (can is a kind of container).
'p'+'can'='pcan'
'eli' put into 'pcan' is 'PELICAN'.
(Other definitions for pelican that I've seen before include "Large bird with pouch in bill for storing fish" , "Aquatic bird with pouch" , "Water bird with throat pouch for fish" , "Large aquatic bird" , "one with huge bill" .)