Managed to suppress party as a health hazard (5)
I believe the answer is:
radon
'a health hazard' is the definition.
(radioactive element)
'managed to suppress party' is the wordplay.
'managed' becomes 'ran' (I've seen this in another clue).
'to suppress' means one lot of letters goes inside another.
'party' becomes 'do' (do is a kind of party).
'ran' enclosing 'do' is 'RADON'.
'as' is the link.
(Other definitions for radon that I've seen before include "Gaseous element, Rn" , "Natural gas considered a hazard to health" , "Rare noble gas" , "Colourless gas, atomic number 86" , "gets no reaction" .)