Transmit commercial plugging port (5)
I believe the answer is:
radio
'transmit' is the definition.
(thesaurus)
'commercial plugging port' is the wordplay.
'commercial' becomes 'ad'.
'plugging' indicates putting letters inside (I've seen this in other clues).
'port' becomes 'rio' (I've seen this before).
'ad' inserted inside 'rio' is 'RADIO'.
(Other definitions for radio that I've seen before include "It used to be called the wireless" , "Communications device" , "Communications receiver" , "send a message" , "Transistor" .)