Head of army strips standing up in bed? (6)
I believe the answer is:
asleep
'in bed?' is the definition.
(I've seen this before)
'head of army strips standing up' is the wordplay.
'head of army' becomes 'a' (I am not sure about this - if you are sure you should believe this answer much more).
'strips' becomes 'peels' (peeling is a kind of stripping).
'standing up' says the letters should be written in reverse (in a down clue up is reverse order).
'peels' back-to-front is 'sleep'.
'a'+'sleep'='ASLEEP'
(Other definitions for asleep that I've seen before include "Knitting up the ravelled sleeve of care" , "Elapse (anag)" , "In the arms of Hypnos" , "Napping" , "Dozing" .)