Secret hide close to nest (6)
I believe the answer is:
covert
'secret' is the definition.
('covert' can be similar in meaning to 'secret')
'hide close to nest' is the wordplay.
I cannot quite understand how this works, but
'hide' could be 'cover' (covering is a kind of hiding) and 'cover' is found within the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for covert that I've seen before include "Hidden - thicket" , "Hidden, secret" , "Area of undergrowth in which animals hide" , "Concealed - vector (anag)" , "Concealed like fox's liar" .)