Implant built-in system - be dynamic! (5)
I believe the answer is:
embed
'implant' is the definition.
(I know that implant can be written as embed)
'built-in system be dynamic' is the wordplay.
'built in' indicates a hidden word.
'EMBED' is hidden in the letters of 'system be dynamic'.
(Other definitions for embed that I've seen before include "Fix securely" , "Put entirely inside something else" , "Firmly put down" , "Enclose snugly" , "the opposite of 19 [DEBUNK]?" .)