Dad possesses some disapproving expressions (6)
I believe the answer is:
frowns
'some disapproving expressions' is the definition.
The answer and definition can be both related to communication as well as being plural nouns.
Maybe there's a link between them I don't understand?
'dad possesses' is the wordplay.
'dad' becomes 'fr' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'possesses' becomes 'owns' ('own' can be a synonym of 'possess').
'fr'+'owns'='FROWNS'
Can you help me to learn more?
(Other definitions for frowns that I've seen before include "Shows displeasure" , "Scowls" .)