Napping, the general is swallowed by snake (6)
I believe the answer is:
asleep
'napping' is the definition.
('asleep' can be similar in meaning to 'napping')
'the general is swallowed by snake' is the wordplay.
'the general' becomes 'lee' (Lee is an example).
'is swallowed by' is an insertion indicator.
'snake' becomes 'asp' (asp is a kind of snake).
'lee' going into 'asp' is 'ASLEEP'.
(Other definitions for asleep that I've seen before include "not paying attention" , "In slumber" , "Having nodded off" , "Slumbering" , "Dead to the world" .)