Struggle with incomplete catchphrase (6)
I believe the answer is:
slogan
'catchphrase' is the definition.
(eg a political catchphrase)
'struggle with incomplete' is the wordplay.
'struggle' becomes 'slog' (I can't justify this - if you can you should believe this answer much more).
'with' becomes 'and'.
'incomplete' means to remove the last letter.
'and' with its last letter removed is 'an'.
'slog'+'an'='SLOGAN'
Can you help me to learn more?
(Other definitions for slogan that I've seen before include "Marketing phrase" , "'Motto, watchword (6)'" , "Shibboleth" , "advertising catch phrase" , "War cry - advertising jingle" .)