Slogan there's something infectious about? (5,6)
I believe the answer is:
catch phrase
'slogan' is the definition.
(I've seen this before)
'something infectious about?' is the wordplay.
I cannot quite understand how this works, but
'about?' could be 'ca' (abbreviation for 'circa') and 'ca' is located in the answer.
This explanation may well be incorrect...
'there's' is the link.
Can you help me to learn more?
(Other definitions for catch phrase that I've seen before include "Familiar words (of comedian)" , "Well-known sentence" , "Oft repeated slogan" .)