Smell almost not as much - effect of runny nose? (8)

'much effect of runny nose?' is the definition.
I can't judge whether this definition defines the answer.

'smell almost not' is the wordplay.
'smell' becomes 'sniff' (sniff is a kind of smell**).
'almost' means to remove the last letter (most of the word but not all of it).
'not' becomes 'less' (I've seen this in other clues).
'less' with its last letter taken off is 'les'.
'sniff'+'les'='SNIFFLES'

'as' is the link.

Can you help me to learn more?