Unmasking former partner showing off (8)
I believe the answer is:
exposing
'unmasking' is the definition.
The answer and definition can be both to do with communicating as well as being present participle verbs.
Maybe there's a link between them I don't understand?
'former partner showing off' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'showing off' becomes 'posing' (I am not sure about this - if you are sure you should believe this answer much more).
'ex'+'posing'='EXPOSING'
Can you help me to learn more?
(Other definitions for exposing that I've seen before include "Showing up" , "Uncovering" , "Subjecting to light, making known" , "outing" .)