Show lettuce concealing little bird (5)
I believe the answer is:
owlet
'little bird' is the definition.
(I've seen this before)
'show lettuce concealing' is the wordplay.
'concealing' indicates a hidden word.
'OWLET' can be found hidden inside 'show lettuce'.
(Other definitions for owlet that I've seen before include "One may give a little screech" , "Nestling" , "Wise baby bird?" , "Baby bird; moth" , "Small hooter" .)