Snake outside shelter catching zeds (6)
I believe the answer is:
asleep
'snake outside shelter catching zeds' is the definition.
I can't judge whether this definition defines the answer.
'snake outside shelter' is the wordplay.
'snake' becomes 'asp' (asp is a kind of snake).
'outside' indicates putting letters inside.
'shelter' becomes 'lee' (as in lee side, the side sheltered from wind).
'asp' enclosing 'lee' is 'ASLEEP'.
Can you help me to learn more?
(Other definitions for asleep that I've seen before include "Like kippers" , "Dormant; inattentive" , "In the Land of Nod" , "In the arms fo Morpheus" , "in bed?" .)