Bird that's flown to test the water (4)
I believe the answer is:
kite
'bird' is the definition.
(kite is a kind of bird)
'that's flown to test the water' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'that's' could be 'ie' and 'ie' is found within the remaining letters.
A single letter 'k' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for kite that I've seen before include "Small hawk" , "Kind of toy flown on string" , "Toy; aircraft (dated)" , "Plaything flown in the wind" , "Wind-borne toy" .)