Seconds in plenty with tenderloin put in place (4)
I believe the answer is:
lieu
'place' is the definition.
(as in the phrase 'in lieu of')
I don't understand the rest of the clue.
(Other definitions for lieu that I've seen before include "Place - position" , "In ... of; in exchange for" , "'In ..., instead (4)'" , "The substitute" , "Stead - place" .)