Small advance when penning good material for advert (6)
I believe the answer is:
slogan
'material for advert' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
I also know that 'advert' relates to this answer.
'small advance when penning good' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'advance when' becomes 'loan' (an advance is a loan. I am not sure about the 'when' bit.).
'penning' is an insertion indicator.
'good' becomes 'g' (abbreviation).
'loan' placed around 'g' is 'logan'.
's'+'logan'='SLOGAN'
Can you help me to learn more?
(Other definitions for slogan that I've seen before include "Word or phrase adopted as motto" , "Ad. catchphrase" , "Rallying cry" , "'Motto, watchword (6)'" , "Battle cry - advertising phrase" .)