Rambling company has essential cover (10)
I believe the answer is:
incoherent
'rambling' is the definition.
(similar in meaning)
'company has essential cover' is the wordplay.
I cannot really understand how this works, but
'company' could be 'co' (abbreviation) and 'co' is located in the answer.
'essential' could be 'inherent' (I've seen this before) and 'inherent' is present in the leftover letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
(Other definitions for incoherent that I've seen before include "Internally inconsistent" , "Confused" , "drunk?" , "rambling" , "Unintelligible" .)