Agent, having secured shelter, ready to go out? (6)
I believe the answer is:
sleepy
'ready to go out?' is the definition.
('out' can mean asleep)
'agent having secured shelter' is the wordplay.
'agent' becomes 'spy' (spy is a kind of agent).
'having secured' means one lot of letters goes inside another.
'shelter' becomes 'lee' (as in lee side, the side sheltered from wind).
'spy' placed around 'lee' is 'SLEEPY'.
(Other definitions for sleepy that I've seen before include "Soporific" , "Dwarf" , "Drowsy - without excitement" , "Doc's nodding pal" , "Quiet" .)