Intend hospital department to receive constant, mostly firm support (13)
I believe the answer is:
accompaniment
'support' is the definition.
(synonyms)
'intend hospital department to receive constant mostly firm' is the wordplay.
I cannot quite see how this works, but
'constant' could be 'e' (mathematics: 2.71) and 'e' is located in the answer.
'firm' could be 'co' (a firm is a company) and 'co' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for accompaniment that I've seen before include "Supporting musical part" , "Something subsidiary that is added" , "Supporting musical line" , "Backing" , "Complement" .)