Very bad cold minimised with spirit -- gosh! (6)
I believe the answer is:
crummy
'very bad' is the definition.
(I've seen this before)
'with spirit gosh' is the wordplay.
'with' becomes 'c' (I can't justify this - if you can you should give a lot more credence to this answer).
'spirit' becomes 'rum' (I've seen this before).
'gosh' becomes 'my' (both are old-fashioned expressions of surprise).
'c'+'rum'+'my'='CRUMMY'
'cold minimised' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for crummy that I've seen before include "Dirty and inferior" , "Poor" , "Inferior (colloq.)" , "Very bad" .)