Outside hospital Helen's aunt is developing dangerous condition (13)

'dangerous condition' is the definition.
'unhealthiness' can be an answer for 'condition' (unhealthiness is a kind of condition). I am not certain of the 'dangerous' bit.

'outside hospital helen's aunt is developing' is the wordplay.
'outside' is an insertion indicator.
'hospital' becomes 'H' (abbreviation for hospital).
'developing' is an anagram indicator (letters developed into a new form).
'helens'+'aunt'+'is'='helensauntis'
'helensauntis' with letters rearranged gives 'unealthiness'.
'h' going inside 'unealthiness' is 'UNHEALTHINESS'.

Can you help me to learn more?