Rubbish engineers, disgusting (6)
I believe the answer is:
revile
'rubbish' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their base form.
Maybe they are linked in a way I don't understand?
'engineers disgusting' is the wordplay.
'engineers' becomes 're' (abbreviation for Royal Engineers).
'disgusting' becomes 'vile' (I've seen this in another clue).
're'+'vile'='REVILE'
Can you help me to learn more?
(Other definitions for revile that I've seen before include "Abuse verbally" , "Criticise - abuse" , "Upbraid or abuse" , "Vilify" , "Abusively criticise" .)