Catchword meaning nothing in slang, perhaps (6)
I believe the answer is:
slogan
'catchword' is the definition.
(synonyms)
'nothing in slang perhaps' is the wordplay.
'nothing in' becomes 'o' (I've seen this in other clues).
'perhaps' indicates an anagram.
'o'+'slang'='oslang'
'oslang' anagrammed gives 'SLOGAN'.
'meaning' is the link.
(Other definitions for slogan that I've seen before include "short political statement" , "Shibboleth" , "Catchy phrase in advertisement etc" , "Logo" , "Memorable advertising phrase" .)