Still around at hospital, melon variety causing illness (10)
I believe the answer is:
pathogenic
'causing illness' is the definition.
(pathogens cause illnesses)
'still around at hospital melon' is the wordplay.
'still' becomes 'pic' (short for picture).
'around' indicates putting letters inside.
'hospital' becomes 'H' (abbreviation for hospital on maps).
'melon' becomes 'ogen' (I've seen this before).
'at'+'h'+'ogen'='athogen'
'pic' enclosing 'athogen' is 'PATHOGENIC'.
'variety' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Another definition for pathogenic that I've seen is " Causing disease".)