Be cause of criminal sit-in by entrance (9)
I believe the answer is:
instigate
'be cause' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?
'criminal sit-in by entrance' is the wordplay.
'criminal' indicates an anagram.
'by' means one lot of letters go next to another.
'entrance' becomes 'gate' (type of entrance).
'sit' anagrammed gives 'sti'.
'sti' after 'in' is 'insti'.
'insti'+'gate'='INSTIGATE'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for instigate that I've seen before include "Start" , "Set off or stir up" , "I get saint to urge or incite" , "Urge on - teasing it (anag)" , "Urge and bring about" .)