Alternately lay signage here on its back (5)
I believe the answer is:
lying
'here on its back' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'alternately lay signage' is the wordplay.
'alternately' indicates alternate letters.
'lay'+'signage'='laysignage'
The alternating letters of 'laysignage' are 'LYING'.
Can you help me to learn more?
(Other definitions for lying that I've seen before include "Not standing" , "Prostrate -- prone" , "So one can't stand" , "Flat" , "Telling untruths" .)