Duck's rest, dropping wings and head (6)
I believe the answer is:
escape
'duck's' is the definition.
(I've seen this before)
'rest dropping wings and head' is the wordplay.
'dropping wings' says to take the centre.
'and' is a charade indicator (letters next to each other).
'head' becomes 'cape' (both can mean a piece of land jutting over the sea).
The centre of 'rest' is 'es'.
'es'+'cape'='ESCAPE'
(Other definitions for escape that I've seen before include "Evade" , "Get away from captivity" , "Decamp" , "performance by Houdini?" , "'Break free, get away (6)'" .)