Observe married men in bed (7)
I believe the answer is:
comment
'observe' is the definition.
(commenting is a kind of observing)
'married men in bed' is the wordplay.
'married' becomes 'm'.
'in' indicates putting letters inside.
'bed' becomes 'cot' (cot is a type of bed).
'm'+'men'='mmen'
'mmen' placed inside 'cot' is 'COMMENT'.
(Other definitions for comment that I've seen before include "Explanatory note" , "How suitable for Le Monde" , "observation" , "offer opinion" , "Leader writer's forte" .)